Note 17 — BOOK XI.

[Pg 512][17] The liquation of these low-grade copper "bottoms" required that the liquated lead should be re-used again to make up fresh liquation cakes, in order that it might eventually become rich enough to warrant cupellation. In the following table the "poor" silver-lead is designated (A) the "medium" (B) and the "rich" (C). The three charges here given are designated sixth, seventh, and eighth for purposes of reference. It will be seen that the data is insufficient to complete the ninth and tenth. Moreover, while the author gives directions for making four cakes, he says the charge consists of five, and it has, therefore, been necessary to reduce the volume of products given to this basis.

6th Charge.7th Charge.8th Charge.

Amount of copper bottoms176.5 lbs.176.5 lbs.176.5 lbs.

Amount of lead282.4 lbs. (slags)564.8 lbs. of (A)635.4 lbs. of (B)

Amount of de-silverized lead494.2 lbs.211.8 lbs.141.2 lbs. (A)

Weight of each cake238.3 lbs.238.3 lbs.238.3 lbs.

Average value of charge per ton22 ozs. 5 dwts.35 ozs. 15 dwts.50 ozs. 5 dwts.

Per cent. of copper18.5%18.5%18.5%

Average value per ton original copper97 ozs. 4 dwts.97 ozs. 4 dwts.97 ozs. 4 dwts.

Average value per ton of90 ozs. 2 dwts. (slags)28 ozs. 5 dwts. (A)28 ozs. 5 dwts. (A)

Average value per ton of3 ozs. 1 dwt. (lead)3 ozs. 1 dwt. (lead)42 ozs. 10 dwts. (B)

Weight of liquated lead550.6 lbs.

Average value of the liquated lead per ton28 ozs. 5 dwts. (A)42 ozs. 10 dwts. (B)63 ozs. 16 dwts. (C)

Weight of exhausted liquation cakes225.9 lbs.

Average value of the exhausted liquation cakes per ton12 ozs. 3 dwts.

Weight of liquation thorns169.4 lbs.

Average value of the liquation thorns per ton18 ozs. 4 dwts.

Extraction of silver into the liquated lead71%