210 On the Limits of Vaporization. [1830. 



but when a little pure ammonia was added to it, a very faint 

 precipitate of oxalate of lime was produced. 



No. 6. Bottle, little solution of potash ; tube, white arsenic 

 in pieces and powder. This bottle was opened because of the 

 appearances, in October 1829, having then remained three 

 years undisturbed. The arsenious acid was to all appearance 

 unchanged. The solution of potash was turbid and foul. On 

 chemical examination, it proved to have acted powerfully on 

 the glass. It had dissolved so much silica as to become a soft 

 solid, by the action of an acid, and it had also dissolved a con- 

 siderable quantity of lead ; but there was no trace of arsenious 

 acid in it ; so that this substance, although abundantly volatile 

 at 600, had not risen in vapour when aqueous vapour and air 

 were present at common temperatures. 



No. 7 was some of the sulphuric acid used in these expe- 

 riments, preserved for comparison. 



No. 8. Bottle, solution half sulphuric acid, half water ; tube, 

 pieces of muriate of ammonia. When this bottle was opened, 

 the pieces of muriate of ammonia presented no appearance 

 of change ; there was no moisture about them, nor any ap- 

 pearances of dissection that I could distinguish. The diluted 

 sulphuric acid being examined by sulphate of silver, gave no 

 evidence of muriatic acid ; so that muriate of ammonia appears 

 fixed under these circumstances. 



No. 9. Bottle, a little solution of persulphate of iron ; tube, 

 crystals of the ferro-prussiate of potash. Both were unchanged ; 

 there was no appearance of prussian blue about either the 

 crystals or solution ; neither of the salts had been volatilized. 



No. 10. Bottle, a little solution of potash; tube, fragments 

 of calomel. Here the potash had acted upon the glass, as in 

 No. 6 ; but, with respect to the calomel, the volatility of which 

 was in question, there was not the slightest trace of such an 

 effect. No black oxide nor other substance existed in the 

 potash solution, which could allow the presumption that any 

 calomel had passed. 



No. 11. Bottle, solution of potash; tube, fragments of cor- 

 rosive sublimate. Here the potash had acted on the glass as 

 before ; carbonic acid had also gained access by the stopper ; 

 so that no caustic potash was present ; but there were distinct 

 appearances of the sublimation of corrosive sublimate, and 



