446 On the Immersion of Copper in Muriatic Acid, 



No. 1, That weighed 53 grains, now weighed ... 39^ grains. 



Loss 1 3^ grains. Equal to 25*4' per cent. 

 No. 2, That weighed 30 grains, now weighed ... 11^ — 

 Loss 18^ grains. Equal to 61*6 per cent. 



No. 3. Unrefined copper flattened, 39 J grs.,"! -q 



now weighed ... j 



Loss 20i grains. Equal to 50 per cent. 

 No. 4. Unrefined copper bar, 42 grs., now weighed 38^ — 



Loss 3^ grains. Equal toSy^^^ percent. 

 It would appear from this experiment that the unrefined 

 copper resists waste in the muriatic acid, in the same way, 

 and to nearly the same extent, as in the cementation with 

 lime mentioned in my last previous paper, p. 325. 



In corroboration of this fact, we may take the following abs- 

 tract of another series of experiments, wherein the specimens 

 were weighed three times, at intervals of 48 hours between 

 each weighing. 



Unrefined copper, 1st immersion, lost... 15 percent. 

 Ditto, 2nd do. ... 8y% — 



Ditto, 3rd do. ... 6 — 



29A~ 



... 25-4 — 

 ,.. 9-7 — 

 ... 11-1 — 



46-2 — 

 In favour of the unrefined copper, principally containing 

 tin, — 169 percent. Two pieces of copper, the one pure the 

 other unrefined, were immersed, under similar circumstances, 

 for seven days. The unrefined copper lost 17 per cent, and 

 the pure copper 45 per cent. To ascertain whether the greater 

 indestructibility was owing to the tin which remained in the 

 unrefined copper, I formed a bar of alloy as follows : 



Pure copper ... 2880 grains. 



Block tin ... 84 — 



A proportion of tin about equal to 3 per cent. A piece from 

 this bar, weighing about 183 grains, was exposed for seven 

 days in muriatic acid, at the end of which time it was found 

 to have lost 30 grains, or 16y*^ per cent. The unrefined cop- 

 per above mentioned lost, in the same time and under similar 

 circumstances, 17 per cent., which is a striking correspon- 

 dence. The same piece of tin alloy, at the end of five weeks, 

 was found to have lost in all 76 grains, or 38 J per cent. Pure 



