300 PHILOSOPHICAL TRANSACTIONS. [aNNO 1686. 



(phlegma) a good deal of earth, but scarcely any fixed salt ; from those which 

 were voided from the intestines and bladder, a larger (Quantity of volatile salt 

 with a little sub-acid phlegm and a strong urinous spirit, some fixed salt, and a 

 large proportion of earth ; 6 oz. of these calculi yielded 5 oz. 2 dr. of caput 

 mortuum, about 1-J- scr. salis lixiviosi, and of water (phlegma) impregnated with 

 volatile spirit and volatile salt 5^- dr. besides a small portion adhering to the 

 sides of the receiver. This liquor being collected and mixed together with an 

 addition of sp. vini alcoholiast. and being afterwards subjected to distillation in 

 an alembic, there sublimed from it in the head of the alembic 2-i- scr. of volatile 

 urinous salt. 



3. On the addition of spirit of vitriol to the distilled liquor, it became of a 

 red colour, and at length turbid, with some deposition. When the spirit of 

 vitriol was poured upon the caput mortuum which remained after the distil- 

 lation, or upon the salt lixiviated from it, a violent effervescence was produced, 

 like that which takes place when the same spirit is mixed with salt or oil of tartar. 



Hence Dr. Konig concludes that these calculi consist of a large proportion 

 of earth, a small quantity of volatile salt, and a little acid, obtunded and edul- 

 corated by an urinous salt and spirit.* 



On the height of the Mercury in the Barometer at different Elevations above the 

 Surface of the Earth ; and on the Rising and Falling of the Mercury on the 

 Change of IVeather. By Mr. Edm. Halley. N° 181, p. 104. 



The elastic property of the air has been long since made out by experiments 

 before the Royal Society, and elsewhere ; and the resistance of its spring is 

 found to be nearly equal to the weight or force that compresses it, as also, that 

 the spaces the same air occupies under diflfering pressures, are reciprocally as 

 those pressures ; it has been likewise shown by undoubted experiment, that the 

 specific gravity of the air, near the earth's surface, to that of water was once 

 as 1 to 840, again as 1 to 852, and a third time, in a very large vessel holding 

 10 gallons, as 1 to 86o ; all which, considering the difficulty of the experiment, 

 agree well enough, the mercury standing at all those times about 29|- inches ; 



^ • By conaparing these experimeots, as well as those made by Dr. Slare, and inserted in the follow- 

 ing N* of these Transactions, with the recent analyses of Dr. Hyde Wollaston, (Philosophical Trans- 

 actions for 1797) and other modern experimenters, it will be seen how little the chemists of the 17th 

 century were acquainted with the real nature of these animal concretions ; and to what great perfec- 

 tion have at length been brought the methods of separating and determining their constituent parts. 

 Nevertheless these experiments cannot but be interesting to those who trace the origin and progress 

 of discoveries ; inasmuch as they demonstrate the compound nature of human calculi, their inso. 

 lubility in the vitriolic acid, their solubility in the nitric acid (and according to Dr. Slare in the muriatic 

 acid also) their resolution into fixed and volatije parts, and the extraction of an acid as well as an 

 anamoniacal and urinous product from them, by distillation. 



