Mat 1, 1865.] THE TECHNOLOGIST. 



ON l'HE RAVAGES OP ANTS. 453 



22 carats fine, i.e., it contains 22 parts of pure gold combined with 2 

 parts of alloy, which is either copper or copper and silver. 



2ndly. The division of the carat into 32 parts is expressed by dividing 

 each carat into 4 (carat) grains, and each grain into eights, and then re- 

 porting any particular sample as B (better) or W (worse) tban standard, 

 by the number of carats, grains, and quarters which it may contain more 

 or less than standard, or gold of 22 carats fine — thus, an alloy of 641 

 parts of gold with 127 parts of silver would be W 1 car. 3§ grs., and 

 pure gold would be B 2 car. grs. 



3rdly. The decimal system of expression has recently been exclu- 

 sively adopted at the Bank of England, and their assays are reported 

 accordingly. Fine gold being taken as 10000, an alloy containing half 

 gold and half copper would be 500 - 0, and standard gold will of course 

 be 916-6, &c, or 22-24ths of 1000-0. 



The London price of standard gold is fixed by law at 31. 17 s. 10^d. 

 per ounce ; fine gold is consequently worth 41. 4s. ll-45d per ounce. 



French coin contains one-tenth of alloy. 



Nuggets, especially those of large size, often contain in their inte- 

 rior a large unknown quantity of earthy matter, and their value cannot 

 be ascertained until after they have been melted down and assayed ; 

 but a very rough approximation may be obtained on the following prin- 

 ciple : — Supposing, for example, the specific gravity of gold of the 

 quality contained in the nugget to be estimated as 19 - 0, and the earthy 

 ingredient to consist of quartz and clay of which the specific gravity is 

 2-4 ; the specific gravity of the nugget itself, ascertained by experiment 

 to be 107, and its actual weight 21-4 ounces. Then by the arithmetical 

 rule of alligation 



19 — 10-7= 8-3X 2-4= 19-92 

 19— 2-4=16-6 X 10-7=177-62 



Then as 177-62 : 21-4 : : 19-92 : 2-4 the weight of quartz, &c. 



ON THE RAVAGES OF ANTS. 



BY THE REV. M. J. BERKELEY. 



WE have just received the first report of the Committee of Inquiry on 

 the Ravages of the White Ant in St. Helena, instituted by the present 

 Governor, Sir Charles Elliott. We have little experience in this country 

 of the destructive powers of ants, though they prove occasionally a 

 source of considerable annoyance in houses where they are difficult to 

 extirpate. It is mostly in our woods that we see what powers of 

 destruction they have when once they attack a tree, which they soon 

 reduce to the appearance of a coarse honeycomb. In one or two 



