i 3 o EFFECTS of HEAT 



tween the filex and the carbonate. The fhell, fufed in the ex- 

 periment, difiblved entirely in the acid, with violent effervef- 

 cence. 



In the three laft experiments, and in feveral others made at 

 the fame time, the carbonate had not been weighed ; but no 

 water being introduced to ailift the compreflion, it is probable 

 there was much lofs by internal calcination ; and owing doubt- 

 lefs to this, the carbonates have crumbled almoft entirely co 

 duft, while the compounds which they had formed with lilex 

 remain entire. 



On the 13th of March, I made a fimilar experiment, in which, 

 befides fome pounded oyfter-fhell, I introduced a mixture of 

 chalk, with 10 per cent, of lilex intermixed, and ground to- 

 gether in a mortar with water, in a date of cream, and then 

 well dried. The contents of the tube when opened, were 

 difcharged with fuch violence, that the tube was broken to 

 pieces > but I found a lump of chalk, then in a Hate of 

 white marble, welded to the compound \ which laft, in its 

 fracture, fhewed that irregular black colour, interfperfed 

 roughly through a cryftalline mafs, that belongs to the al- 

 pine marbles, particularly to the kind called at Rome Cipol- 

 line. It was very hard and firm ; I think unufually fo. It effer- 

 velced conflantly to the laft atom, in diluted nitric acid, but 

 much more fluggifhly than the marble made of pure chalk. A 

 cloudinefs appeared pervading all the liquid. When the 

 eftervefcence was over, a feries of bubbles continued during 

 the whole day in the acid, without any difpofition to burft, 

 or rife to the furface. After ftanding all next day and night, 

 they maintained their ftation \ and the folution being ftirred, 

 was found to be entirely agglutinated into a tranfparent jelly, 

 breaking with fharp angles. This experiment affords a direct 

 and pofitive proof of a chemical union having taken place be- 

 tween the carbonate and lilex. 



VI. 



