TOMATO PULP (continued 2)

1 Cylinder of heavy glass, lipped, height 12 inches, diameter 2 inches.

1 Chemical thermometer, graduated in Fahrenheit system up to 212° F.

Since this apparatus is likely to be broken, it is well for each plant that contemplates using the method to equip itself with at least two of each item mentioned above.

The Brix hydrometer mentioned above is suggested because it is a stock article handled by all dealers in chemical apparatus and can be secured quickly. It has the disadvantage that it is relatively large, and in order to use it the filtrate must be prepared in much larger quantity than would be required by a smaller hydrometer. By placing orders well in advance with dealers in chemical apparatus special hydrometers may be made with a bulb about one-half inch in diameter and with a total length of five or six inches. Such hydrometers could be used with a cylinder as small as one inch in diameter. They would require much less liquor than is necessary for the Brix hydrometer and therefore would enable the analyst to obtain results much more quickly. In securing such hydrometers it would be well to order several at a time, since it would require several weeks to replace any that may be broken.

The details of the method are as follows:

Place a piece of cotton cloth of about the texture of ordinary glass toweling over a clean, dry container 10 or 12 inches in diameter or over a No. 10 can. Pour on the cloth a suitable amount of the pulp or cyclone juice to be examined, pick the cloth up by the corners and squeeze gently to separate the greater part of the insoluble solids. The strained liquid left in the vessel will be more or less turbid, according to the pressure exerted in squeezing. The amount of insoluble material producing this turbidity, however, is not usually sufficient to interfere with the examination of the product by means of a hydrometer. If, however, it is necessary to exert considerable pressure to get the amount of filtrate desired and the turbidity is therefore considerable it will be necessary to pass the liquor through a second filter, which, of course, may be done quickly.

Transfer this strained liquid, which for the sake of convenience we will designate as “filtrate,” to the 2-inch cylinder described above, and lower the Brix hydrometer into it until the hydrometer floats. When the hydrometer, becomes stationary, the reading on the stem is taken. In reading the hydrometer it will be noted that, owing to the meniscus, the liquid immediately at the stem rises one or two divisions above the general surface. The reading at the lowest point of the surface is desired. In reading the stem, therefore, allowance for the meniscus should be made and a reading recorded one or two divisions on the scale below the extreme height of the meniscus on the stem. The reading so obtained is recorded as the Brix hydrometer reading of the filtrate.

After determining the Brix reading of the filtrate from the tomato pulp, the corresponding specific gravity of the pulp may be obtained from Table 9. The result obtained by the method should be corrected to the temperature of 68° F., according to Table 8. If it is desired to use the reading of the filtrate from cyclone juice for the purpose of controlling the evaporation of tomato pulp, suitable directions are given below under “Evaporation to Specific Gravity Desired.”

IMPORTANCE OF ACCURACY IN DETERMINING SPECIFIC GRAVITY

The description of the tables given in the following page is intended for those operators who desire to take the trouble to obtain the specific gravity of raw product. Where, as is often the case, the pulp is sold under definite specifications for specific gravity, the care necessary to make these observations with a considerable degree of accuracy will be found to be an economy.

If a product be shipped that is materially below the specific gravity stipulated, the manufacturer will of course be docked and the loss will be considerable. On the other hand, the specific gravity should not be materially above the specifications. The buyer, who is usually a manufacturer of ketchup, desires the pulp of the specific gravity stipulated, and a higher degree of concentration is therefore not a mark of superiority in pulp intended for that purpose. Moreover, material increase in concentration above the specifications of the purchaser causes considerable loss by reason of reduced volume. For instance, 100 gallons of pulp with a specific gravity of 1.036 are equivalent to 103 gallons of a pulp with a specific gravity of 1.035. Again, 100 gallons of pulp with a specific gravity of 1.040 are equivalent to 114.7 gallons of pulp with a specific gravity of 1.035.

When these figures are considered with reference to the entire output of the season, it is apparent that the determination of the specific gravity of the final product is of considerable importance, and will warrant care and, if necessary, the employment of a man who is competent to do the work accurately.

This is well illustrated by an experience of one of the large pulp makers, who was selling pulp under specification of 1.035 specific gravity. Owing partly to an error in his specific gravity apparatus, he was actually turning out pulp of a specific gravity varying from 1.040 to 1.050. In other words, each 100 cases of pulp he delivered were equivalent to from 115 to 126 cases of pulp of 1.035 specific gravity. While this manufacturer was using the greater part of the pulp himself, he had contracted to sell a considerable amount of it, and all that was supplied before the error was noticed was sold at a loss, whereas after the error was discovered he supplied pulp well above the specifications of the buyer at a substantial profit. Even then his profit was not what it should have been. His output would have been 10 per cent greater than it was if the specific gravity of his product had just complied with his specifications.

Another manufacturer who sold his pulp under the specification of 1.035 specific gravity, received a complaint from one of the largest buyers of pulp in the country that the specific gravity was low. The manufacturer then examined samples, which he had retained in his possession, of the various runs, using the method described on page 41, under the head of “Specific gravity of cold pulp without centrifuging.” Seventeen samples in all were examined, and he obtained an average specific gravity of 1.0276. The purchaser had reported a specific gravity of 1.0315–.0039 higher than that obtained by the maker. The manufacturer then brought duplicate samples to this laboratory and the specific gravity was determined in all of them by the method described on page 34, “After centrifuging to eliminate air bubbles.”

While this work was being done the manufacturer himself desired to check the mechanical centrifuge, and attempted to remove the air bubbles from the same samples by swinging the specific gravity cups by hand. He made a special effort to remove the air bubbles in this way, devoting nearly a day to the examination of the 17 samples. Notwithstanding his unusual care, his average specific gravity was 1.0318, while the centrifuge method gave 1.0328. It will be noted that the specific gravity as determined by the centrifuge method was .0013 higher than that obtained by the purchaser, though the latter used a more accurate method than has ordinarily been employed in this determination. This difference has ordinarily been regarded in the industry as insignificant. It is apparent that it is not negligible, however, when we consider that the difference in yield involved amounts to over 4.5 gallons in 100 gallons of pulp.

It is true that all these results are lower than the specifications for which this particular pulp was sold, but the incident illustrates the importance of an accurate determination of specific gravity.

EVAPORATION TO THE SPECIFIC GRAVITY DESIRED

Manufacturers of tomato pulp have considerable difficulty in securing a product of uniform concentration and in determining at what point to stop evaporation. Some manufacturers turn off the steam when it is believed that the concentration has gone far enough and make a hasty determination of specific gravity. If it is found the concentration is not as great as is desired, heating is resumed for a time and the specific gravity again determined. Others make but one determination of specific gravity when it is believed that the desired concentration has been reached, and if it is found to be underconcentrated, continue the evaporation for a length of time which experience has indicated to be necessary. Neither of these methods of operating is satisfactory. They involve a great deal of work and the concentration of the product obtained is not sufficiently uniform. Moreover, the determination of specific gravity of hot pulp is very inaccurate (see p. 44).

A method of employing a gauge stick is believed to be simpler and more practicable.

Some manufacturers who desire to work with the simplest possible methods, even at the sacrifice of a high degree of control over the concentration of their products, measure the volume of cyclone juice introduced into the evaporating tank; and when it is believed that the concentration is sufficient, measure the depth of the evaporated product in the tank, the steam being momentarily turned off for that purpose and the measurement being taken after the foam subsides. This method was outlined in detail in a trade paper article published from this laboratory in 1918. The method is somewhat inaccurate, because it is based on the measurement of cyclone juice as it flows from the cyclone and which therefore contains a large amount of air. This air materially increases the volume of the pulp and consequently the amount of finished pulp calculated from the volume of cyclone juice containing this air is greater than can actually be obtained. Some manufacturers of pulp have found the method practicable, however, by making a correction based on factory experience on the amount of pulp which the method indicates should result from the evaporation of each bath. This method also calls for the use of measuring tanks, which many manufacturers do not have and do not care to provide. The method is therefore not repeated here, but the laboratory has a number of reprints of the trade paper article which are available to any who desire more detailed information regarding the matter.

The following method has been found more accurate and more convenient than the one mentioned above. It has the special advantage that it is based on the examination of the cyclone juice after the juice has been heated to a sufficient extent to “break” the foam.

In using this method, the manner in which the cyclone juice is prepared is immaterial. The tomatoes may be broken by steam or mechanical breaker and may be cycloned hot or cold. The steam may be turned into the coils as soon as they are covered and the cyclone juice may run into the evaporating tank until the tank is filled.

Finally, when the last of the cyclone juice is added and the contents of the tank are boiling vigorously, the steam is momentarily turned off. The volume is then determined by means of a gauge stick and a sample is withdrawn, filtered and the specific gravity or degrees Brix determined as described on page 50. The extent to which evaporation must be continued to secure pulp of the desired specific gravity is determined by Table 9.

This table gives in the first four columns the specific gravity of the partially concentrated pulp taken from the evaporating tank, the per cent of solids of the same, the specific gravity of the filtrate and the Brix reading of the filtrate. In order to use the tables, it is only necessary to make use of one of these columns.

This method of operation can be simplified and more accurate results obtained by equipping each evaporating tank with a one-inch gage glass extending the full height of the tank. The gage glass should be open at the top and connected with the bottom of the tank by a pipe equipped with a valve. Before the tank is filled with cyclone juice the valve is turned off and the gage glass filled with water. Steam is turned on as soon as the pipes are covered and the foam is “broken” quickly without trouble that was experienced in heating the tank filled with cool pulp. The heat is continued while the tank is filled to the desired height with the pulp. The steam is then momentarily turned off and the valve at the top of the gage glass opened to permit the water in the gage glass to equalize in height with the partly concentrated pulp within the tank. The height of water in the gage glass is read by a scale attached, the sample of the pulp taken for examination and the steam again turned on.

There is ample time to determine the specific gravity of the sample of partly concentrated pulp and from its volume as obtained by the gage glass to calculate the volume to which the pulp should be evaporated to secure the desired specific gravity in the finished product. The specific gravity of the sample may be taken by any of the methods described in the chapter on “Determination of specific gravity.” More accurate results can be obtained by pouring the sample of pulp as soon as it is taken into a large loosely stoppered flask and holding the flask with constant agitation in a tub of ice water until it is brought to about the temperature of the room.

Having determined the volume (when heated to the boiling point) of a batch of cyclone juice or of pulp at any stage of its manufacture and its specific gravity (at 68° F.), each of the last five columns of the table gives a factor by which the volume of the partially evaporated pulp may be multiplied to determine the volume of pulp of the specific gravity given at the top of the column. Since both measurements are taken at the boiling point the question of temperature need not be considered.

Table 8.—Corrections for Specific Gravity and Brix[19] Readings at Different Temperatures to 68 Degrees F. (20 Degrees C.)

Corrections to be subtracted from specific gravity or degrees Brix.

Temperature Corrections

Deg. F.Deg. C. Sp. Gr.Brix.

50 10.0 .0017 .38

51 10.6 .0016 .36

52 11.1 .0016 .35

53 11.7 .0015 .33

54 12.2 .0014 .31

55 12.8 .0014 .30

56 13.3 .0013 .28

57 13.9 .0012 .26

58 14.4 .0011 .24

59 15.0 .0010 .22

60 15.6 .0009 .20

61 16.1 .0009 .18

62 16.7 .0008 .16

63 17.2 .0007 .13

64 17.8 .0006 .11

65 18.3 .0004 .08

66 18.9 .0003 .05

67 19.4 .0002 .03

Corrections to be added to specific gravity or degrees Brix.

Temperature Corrections

Deg. F.Deg. C. Sp. Gr.Brix.

69 20.6 .0002 .03

70 21.1 .0003 .05

71 21.7 .0004 .08

72 22.2 .0006 .11

73 22.8 .0007 .15

74 23.3 .0009 .18

75 23.9 .0011 .21

76 24.4 .0012 .24

77 25.0 .0013 .28

78 25.6 .0015 .32

79 26.1 .0017 .35

80 26.7 .0018 .39

81 27.2 .0019 .42

82 27.8 .0021 .46

83 28.3 .0023 .49

84 28.9 .0024 .54

85 29.4 .0026 .58

86 30.0 .0027 .62

87 30.6 .0029 .66

88 31.1 .0031 .70

Table 9.—Equivalent Volumes of Pulp of Different Degrees of Concentration

Tomato pulp Filtrate from pulp Factor by which to multiply volume of pulp of given specific gravity to ascertain volume of pulp with equivalent solid content and with specific gravity of

Specific gravity at 68° F. Per cent solids Specific gravity at 68° F. Degrees Brix at 68° F. 1.030 1.035 1.040 1.045 1.050

1.0125 2.79 1.0108 2.78 .384 .326 .283 .249 .223

1.0130 2.92 1.0113 2.89 .402 .342 .296 .261 .234

1.0135 3.05 1.0118 3.02 .420 .357 .310 .273 .244

1.0140 3.17 1.0123 3.14 .437 .372 .323 .285 .255

1.0145 3.30 1.0128 3.27 .455 .388 .336 .297 .265

1.0150 3.42 1.0133 3.40 .472 .401 .348 .306 .274

1.0155 3.54 1.0138 3.51 .489 .416 .361 .318 .284

1.0160 3.67 1.0143 3.65 .507 .431 .374 .329 .294

1.0165 3.79 1.0148 3.77 .524 .445 .387 .341 .304

1.0170 3.92 1.0153 3.90 .542 .460 .400 .352 .315

1.0175 4.05 1.0158 4.03 .560 .476 .413 .364 .325

1.0180 4.18 1.0163 4.15 .579 .491 .426 .375 .335

1.0185 4.30 1.0168 4.28 .596 .506 .440 .387 .346

1.0190 4.43 1.0173 4.40 .614 .521 .452 .399 .356

1.0195 4.56 1.0178 4.53 .632 .537 .466 .410 .367

1.0200 4.68 1.0182 4.63 .649 .551 .478 .421 .377

1.0205 4.81 1.0188 4.77 .667 .566 .491 .433 .387

1.0210 4.93 1.0192 4.87 .684 .581 .504 .444 .398

1.0215 5.05 1.0196 4.97 .701 .596 .517 .456 .407

1.0220 5.17 1.0201 5.10 .718 .610 .529 .467 .417

1.0225 5.30 1.0206 5.22 .737 .625 .543 .479 .428

1.0230 5.43 1.0211 5.35 .755 .641 .556 .490 .438

1.0235 5.55 1.0216 5.47 .772 .656 .569 .502 .448

1.0240 5.67 1.0220 5.57 .789 .671 .582 .513 .459

1.0245 5.80 1.0226 5.72 .808 .686 .595 .525 .469

1.0250 5.92 1.0230 5.82 .825 .701 .608 .536 .479

1.0255 6.04 1.0235 5.94 .842 .715 .620 .547 .489

1.0260 6.16 1.0240 6.07 .859 .729 .633 .558 .499

1.0265 6.28 1.0244 6.17 .876 .744 .646 .569 .509

1.0270 6.40 1.0249 6.29 .894 .759 .658 .580 .519

1.0275 6.53 1.0254 6.43 .912 .775 .672 .592 .529

1.0280 6.65 1.0258 6.53 .930 .789 .685 .604 .539

1.0285 6.77 1.0263 6.65 .947 .804 .697 .615 .549

1.0290 6.90 1.0268 6.78 .965 .819 .711 .626 .560

1.0295 7.02 1.0273 6.90 .983 .834 .724 .638 .570

1.0300 7.14 1.0278 7.03 1.000 .849 .737 .649 .580

1.0305 7.26 1.0282 7.13 1.017 .864 .749 .660 .590

1.0310 7.38 1.0287 7.23 1.035 .878 .762 .672 .600

1.0315 7.50 1.0292 7.35 1.052 .893 .775 .683 .610

1.0320 7.63 1.0296 7.45 1.071 .908 .788 .695 .621

1.0325 7.75 1.0301 7.58 1.088 .924 .802 .706 .631

1.0330 7.88 1.0306 7.70 1.107 .939 .815 .718 .642

1.0335 8.00 1.0310 7.80 1.124 .954 .828 .730 .652

1.0340 8.12 1.0315 7.93 1.142 .970 .842 .742 .663

1.0345 8.25 1.0320 8.05 1.160 .985 .855 .753 .673

1.0350 8.37 1.0325 8.16 1.178 1.000 .868 .765 .684

1.0355 8.50 1.0330 8.27 1.197 1.016 .882 .777 .695

1.0360 8.62 1.0334 8.37 1.214 1.031 .895 .788 .705

1.0365 8.74 1.0339 8.50 1.232 1.046 .907 .800 .715

1.0370 8.86 1.0344 8.63 1.249 1.061 .920 .811 .725

1.0375 8.98 1.0349 8.75 1.267 1.076 .933 .823 .735

1.0380 9.10 1.0353 8.85 1.284 1.091 .947 .834 .746

1.0385 9.23 1.0358 8.97 1.303 1.106 .960 .846 .756

1.0390 9.35 1.0363 9.07 1.321 1.122 .974 .858 .767

1.0395 9.48 1.0368 9.20 1.340 1.138 .987 .870 .778

1.0400 9.60 1.0372 9.30 1.358 1.153 1.000 .881 .788

1.0405 9.73 1.0378 9.45 1.377 1.168 1.014 .893 .799

1.0410 9.85 1.0383 9.57 1.394 1.184 1.027 .905 .809

1.0415 9.97 1.0387 9.67 1.412 1.199 1.041 .917 .820

1.0420 10.10 1.0393 9.80 1.431 1.215 1.054 .929 .830

1.0425 10.22 1.0397 9.90 1.449 1.230 1.067 .941 .841

1.0430 10.35 1.0402 10.03 1.468 1.246 1.081 .953 .851

1.0435 10.47 1.0406 10.13 1.486 1.261 1.094 .964 .862

1.0440 10.60 1.0411 10.25 1.505 1.277 1.108 .976 .873

1.0445 10.72 1.0416 10.36 1.523 1.293 1.122 .988 .884

1.0450 10.84 1.0420 10.45 1.540 1.308 1.135 1.000 .894

1.0455 10.96 1.0425 10.57 1.558 1.322 1.148 1.012 .904

1.0460 11.08 1.0429 10.67 1.576 1.338 1.161 1.023 .915

1.0465 11.20 1.0435 10.83 1.594 1.353 1.174 1.035 .925

1.0470 11.33 1.0440 10.93 1.613 1.369 1.188 1.047 .936

1.0475 11.45 1.0445 11.05 1.631 1.384 1.201 1.059 .946

1.0480 11.57 1.0449 11.15 1.649 1.400 1.215 1.071 .957

1.0485 11.70 1.0454 11.27 1.668 1.416 1.229 1.083 .968

1.0490 11.82 1.0459 11.40 1.686 1.432 1.243 1.095 .979

1.0495 11.95 1.0465 11.53 1.705 1.449 1.256 1.107 .990

1.0500 12.07 1.0468 11.60 1.724 1.464 1.270 1.119 1.00

1.0505 12.20 1.0474 11.75 1.743 1.479 1.284 1.131 1.01

1.0510 12.32 1.0478 11.84 1.761 1.495 1.298 1.144 1.02

1.0515 12.45 1.0482 11.93 1.780 1.511 1.311 1.156 1.03

1.0520 12.57 1.0488 12.07 1.797 1.526 1.325 1.167 1.04

1.0525 12.69 1.0492 12.17 1.816 1.542 1.338 1.179 1.05

1.0530 12.81 1.0497 12.30 1.834 1.557 1.351 1.191 1.06

1.0535 12.93 1.0502 12.40 1.852 1.572 1.364 1.203 1.07

1.0540 13.05 1.0506 12.50 1.870 1.588 1.378 1.215 1.08

1.0545 13.18 1.0512 12.65 1.890 1.604 1.392 1.227 1.09

1.0550 13.30 1.0516 12.74 1.908 1.620 1.405 1.239 1.10

1.0555 13.42 1.0520 12.83 1.926 1.635 1.419 1.250 1.11

1.0560 13.55 1.0525 12.95 1.945 1.651 1.433 1.263 1.12

1.0565 13.67 1.0529 13.05 1.964 1.667 1.447 1.275 1.14

1.0570 13.80 1.0534 13.16 1.983 1.684 1.461 1.288 1.15

Table 10.—Specific Gravity and Solids of Tomato Pulp[20]

Specific gravity at 68° F. Per cent solids in vacuo at 70° C.

1.0145 3.30

1.0150 3.42

1.0155 3.55

1.0160 3.67

1.0165 3.80

1.0170 3.92

1.0175 4.05

1.0180 4.18

1.0185 4.30

1.0190 4.43

1.0195 4.56

1.0200 4.68

1.0205 4.81

1.0210 4.93

1.0215 5.05

1.0220 5.17

1.0225 5.30

1.0230 5.43

1.0235 5.55

1.0240 5.67

1.0245 5.80

1.0250 5.92

1.0255 6.04

1.0260 6.16

1.0265 6.28

1.0270 6.40

1.0275 6.53

1.0280 6.65

1.0285 6.77

1.0290 6.90

1.0295 7.02

1.0300 7.14

1.0305 7.26

1.0310 7.38

1.0315 7.50

1.0320 7.63

1.0325 7.75

1.0330 7.88

1.0335 8.00

1.0340 8.12

1.0345 8.25

1.0350 8.37

1.0355 8.50

1.0360 8.62

1.0365 8.74

1.0370 8.86

1.0375 8.98

1.0380 9.10

1.0385 9.23

1.0390 9.35

1.0395 9.48

1.0400 9.60

1.0405 9.73

1.0410 9.85

1.0415 9.97

1.0420 10.10

1.0425 10.22

1.0430 10.35

1.0435 10.47

1.0440 10.60

1.0445 10.72

1.0450 10.84

1.0455 10.96

1.0460 11.08

1.0465 11.20

1.0470 11.33

1.0475 11.45

1.0480 11.57

1.0485 11.70

1.0490 11.82

1.0495 11.95

1.0500 12.07

1.0505 12.20

1.0510 12.32

1.0515 12.45

1.0520 12.57

1.0525 12.69

1.0530 12.81

1.0535 12.93

1.0540 13.05

1.0545 13.18

1.0550 13.30

1.0555 13.42

1.0560 13.55

1.0565 13.67

1.0570 13.80

1.0575 13.92

1.0580 14.05

1.0585 14.17

1.0590 14.29

1.0595 14.42

1.0600 14.54

1.0605 14.67

1.0610 14.79

1.0620 15.03

1.0630 15.27

1.0640 15.52

1.0650 15.77

1.0660 16.02

1.0670 16.27

1.0680 16.52

1.0690 16.77

1.0700 17.02

1.0710 17.27

1.0720 17.51

1.0730 17.76

1.0740 18.00

1.0750 18.25

1.0760 18.50

1.0770 18.75

1.0780 18.99

1.0790 19.24

1.0800 19.48

1.0810 19.72

1.0820 19.97

1.0830 20.22

1.0840 20.47

1.0850 20.72

1.0860 20.96

1.0870 21.21

1.0880 21.46

1.0890 21.70

1.0900 21.95

1.0910 22.20

1.0920 22.45

1.0930 22.70

1.0940 22.94

1.0950 23.18

1.0960 23.43

1.0970 23.68

1.0980 23.93

1.0990 24.18

1.1000 24.43

1.1010 24.67

1.1020 24.92

1.1030 25.18

1.1040 25.42

1.1050 25.67

1.1060 25.91

1.1070 26.16

Illustration: Suppose that when the cyclone juice is all added to the tank the contents of which are vigorously boiling so that they are doubtless of uniform composition, the volume is found by the gauge stick to be 815 gallons. A sample of this partially evaporated pulp is withdrawn and filtered and the filtrate is found to have a Brix reading of 6.90. Let us suppose that the product is to be evaporated to a pulp having a specific gravity of 1.035 and the operator desires to know at what point to turn off the steam. By referring to Table 9 in the column headed by the figure 1.035, we find opposite the Brix reading 6.90 the factor .834. Multiplying the volume of the pulp (815 gallons) by this factor, we obtain 680 gallons. It follows, therefore, that the steam should be turned off when the evaporation has reached such a point that the gauge stick shows the volume of pulp to be 680 gallons.

Table 9 may be used in the same way for calculating the volume of any pulp, hot or cold, of any specified specific gravity equivalent to a certain volume of pulp of any other stated specific gravity when held at the same temperature. For instance, the illustration given above serves equally well to illustrate how the relative value of two finished pulps of different specific gravities may be calculated. It also shows directly the relative value (based on tomato solids alone) of the same volume of two pulps of different gravity.

Illustration: Suppose a shipment contains 1,000 cases of No. 10 cans of pulp thought to have a specific gravity of 1.040 but found on examination to have a specific gravity of 1.0365. What is the value of the pulp in comparison with pulp of specific gravity of 1.040? Turning in Table 9 to the figure 1.0365 in the left-hand column we follow the horizontal line containing that figure to the column headed by specific gravity 1.040. Here we find that .907 is the factor by which to multiply the volume of pulp of a specific gravity 1.0365 to obtain the equivalent volume of pulp of specific gravity 1.040. The answer to our question therefore is 1000 × .907 = 907. In other words pulp of a gravity of 1.0365 judged by the tomato solids it contains, has 90.7 per cent of the value of pulp of the gravity of 1.040.

Table 9 is based on the results obtained from a series of samples of whole tomato pulp and cyclone juice varying in specific gravity from 1.02 to 1.05. The table was extended by calculation to give corresponding values for more dilute cyclone juices and more concentrated products. The lower portion of the table has been repeatedly confirmed by results obtained in the examination of cyclone juice and pulp, but the figures in the higher portion of the table are based on calculation from lower concentrations.

This table is only applicable to pulp to which no other substance, such as salt, has been added. Salt if present to the extent of more than 0.25 per cent can be recognized by the taste. The amount of salt, when any has been added, may be determined by the method given on page 33 and the specific gravity corrected by subtracting from the apparent specific gravity 0.007 for each per cent of salt present. This gives the specific gravity of the salt-free pulp and the corresponding per cent of solids may be obtained from Table 9.