280 PHILOSOPHICAL TRANSACTIONS. [aNNO 1746. 



an olive-colour, and finely polished. The other three, as he was informed, were 

 of the same colour and texture, and one of them larger than either of these 

 which measured one way round 1 2 inches, and the other way 1 1 . 



Experiments. — ^These 2 stones, being sawed asunder, looked like polished 

 marble ; and were found to contain a piece of an iron nail in the middle. The 

 triangular stone weighed 75 grs. above 14- oz. Troy. The other, being the 

 larger, weighed but 2^ grs. short of l6 oz. Troy. 



A fragment of the smaller stone, which in the air weighed \0Z-^ grs. in water 

 weighed 42-iV grs. ; so that its specific gravity is to water, as 170 to 100. A 

 fragment of the larger stone, which weighed in air 83-rV gr. weighed in water 

 of the same degree of warmth, 34-,^;^ gr. so that the specific gravity of this is the 

 same as of the other. 



A quantity of the larger stone, weighing 4 oz. being distilled in a coated retort, 

 yielded 37-ro- gr. above 20 oz. of a strong alkaline spirit, of a brown colour, such 

 as is drawn from hartshorn ; leaving a black coal weighing 7A-J^ gr. short of 2 

 oz. ; 36-^ gr. being converted into air, and otherwise lost in collecting the pro- 

 duce of the distillation ; a small quantity of black oil adhered to the neck of the 

 receiver, and a few drops of this oil appeared in the spirit, when it was first 

 poured off; but after standing some time, it fell to the bottom in the form of a 

 black sediment. The black coal, calcined under a muffle in a very strong fire, 

 lost only 22 grains, and became a white insipid earth. 



A fragment of the great stone, which had lain exposed to the air and weather 

 above 12 months, as mentioned above, weighing in the air 58 gr. weighed in 

 water 2A^ gr. after it had stood a considerable time, that the water might enter 

 its cavities : so that this stone, though seeming of a loose texture, came out not 

 much inferior to the other in specific gravity; this being to water as 163 

 to 100. 



A portion of this stone, in a strong open fire, lost in calcination just half its 

 weight ; becoming, as the former, a white insipid earth ; which, being infused in 

 boiling water, made no alteration in its colour, taste, nor smell. 



Three oz. of this stone distilled, produced 24^^ gr. more than l-j- oz. of the 

 like alkaline spirit as the former yielded, and left a black coal, weighing 1 Q^ gr. 

 above 14^ oz. 



From this chemical analysis, it appears that these stones are compounded 

 chiefly of earth, a large quantity of volatile alkaline salt and water, some oil, and 

 a small quantity of air. From hence it also appears, that the component princi- 

 ples of these stones bear a nearer resemblance to those of hartshorn, than that of 

 the calculus humanus : for, according to Dr. Hales's account, in his Vegetable 

 Statics, experiment N° 51, 241 grains of deer's-horn, being distilled, left a calx 

 weighing 128 gr. ; viz. above half its weight; which shows that horn contains 



