VOL. LXXXVIII.} PHILOSOPHICAL TRANSACTIONS. 255 



which Van Helmont says is preferable to alkaline lixivium. He also says, that 

 when the archeus spirit of urine meets with a volatile earthy spirit, and does not 

 act in a due manner, a concretion will be formed; but in a healthy state, though 

 all urine contains the matter of urinary calculi, no concretion can take place; be- 

 cause the archeus, or vital power of the bladder, counteracts its formation. As 

 to the kind of earth composing calculi, the only distinction of earths, till about the 

 last half century, was into absorbent and non-absorbent ; but, since the absorbent 

 earths were distinguished into calcareous earth, magnesia, and alumina or clay, the 

 calcareous was considered to be the earth of urinary concretions; apparently however 

 for no other reason but its obvious properties, and its extensive diffusion through 

 the whole animal kingdom. 



At length, viz. in 177^, the experiments of the wonderful Scheele were pub- 

 lished in Sweden, but were scarcely known in this country till 1785. These ex- 

 periments exploded the opinion of the earthy nature of calculi, and substituted 

 that of their consisting of a peculiar acid, resembling the succinic, and of a gela- 

 tinous matter, without any earth. Afterwards about -j-f^- of their weight of lime 

 was found by Bergman; which, for a cause now well known, had eluded the acute- 

 ness of Scheele. Though the experiments of Scheele were confessedly unques- 

 tionable, and were ably supported by the learned Bergman, some very eminent 

 chemists, having obtained different results by their own experiments, adopted a 

 different opinion of the composition of these concretions. The immortal, and 

 ever to be deplored, Lavoisier supposed these substances to consist of acidulous 

 phosphate of lime and animal matter, many of them being partially fusible; but 

 still it was the unrivalled Scheele who discovered, that the urine of healthy persons 

 contains superphosphate, or acidulous phosphate, of lime; and who also indicated 

 the experiment which verified his opinion, that phosphate of lime is the basis of 

 bone. 



Experiments have been likewise made, for the most part in a rather desultory 

 way, and most of them by persons but little practised in chemical inquiries, which 

 at least afford evidence, that urinary concretions are very different, with respect to 

 the proportion of the ingredients in their composition, and perhaps also in kind. 

 M. Fourcroy, who however must not be classed with inexperienced chemists, I 

 believe first obtained prussic acid by fire, and by nitric acid, from these concre- 

 tions ; and showed that they sometimes contain phosphate of ammonia and of soda; 

 which may be dissolved out of them by water. M. Fourcroy also says, he found 

 magnesia in the intestinal calculus of a horse; which calculus was a triple combi- 

 nation, of 1 part of phosphate of ammonia, 2 parts of magnesia, and 1 of water, 

 besides traces of animal and vegetable matter. Dr. Link, in a very elaborate dis- 

 sertation, published at Gottingen, in 1788, or urine and calculi, concludes that 

 urinary concretions consist of phosphoric acid, lime, ammonia, oil, the bases of 

 different kinds of gazes, with the acid sublimate of Scheele, though he did not 

 succeed in obtaining it. It is a proof of Dr. Black's sagacity, that he was able to 



