VOL. LXXXVIII.] PHILOSOPHICAL TRANSACTIONS. 263 



found extremely important, as it enables us to interpret many phenomena, in a va- 

 riety of cases besides the present. It now appears, that the inflammation men- 

 tioned in 1 of the above experiments, and which also happened in several others, 

 on evaporation of the nitric solution of the animal oxide, was from the nitrate of 

 ammonia, the nitrum flammans of the old chemists, compounded in those expe- 

 riments. This inflammation takes place sometimes on evaporation of nitric solu- 

 tions, both of urinary concretions, and of urine itself evaporated to the state of 

 soft extract, on account of the ammonia already existing in these substances. 

 The composition of ammonia also explains the disappearance of the whole matter 

 of some sorts of urinary concretions, a very small residue of black matter ex- 

 cepted, by repeated affusion and evaporation of nitric acid, from the solution of 

 them in this menstruum. 



It remains for me to give an account of the 96 grs. of powdery matter left on 

 the paper- strainer, (a) ; which are the insoluble portion, in lye of caustic soda, of 

 300 grs. of urinary concretions. 1. A small portion of the insoluble matter, 

 being exposed to flame with the blow-pipe, did not turn black, nor yield any smell of 

 animal matter; but it became whiter, and I could just agglutinate the powder into 

 one mass, though I was unable to render it fluid. 2. The filtrated liquid, from a 

 little of the matter boiled in water, became very turbid and white with oxalic acid: 

 with lime water was barely curdy; and it did not alter the colour of turnsole, or 

 of violet juice. 3. The matter dissolved completely in muriatic acid, and also in 

 nitric acid, without effervescence. 



This nitric solution, having been evaporated, to carry off most of the free acid, 

 instantly became very curdy on the addition of lime water. It became thick and 

 white on adding sulphuric acid, yielding a copious precipitate of sulphate of lime. 

 One portion of the supernatant liquor on this precipitate, on evaporation, afforded 

 an extract-like matter; which readily melted, as phosphoric acid does when it is 

 mixed with a little earthy matter. To the other portion of this supernatant liquor 

 was added liquid caustic ammonia, producing a precipitate which afforded no sul- 

 phate of magnesia with sulphuric acid. From these experiments it appears, that 

 the above 96 gr. of insoluble matter consisted of phosphate of lime. Accordingly, 

 the 300 gr. of urinary concretions examined, appear to contain, 



Peculiar animal oxide 175 grs. 



Phosphate of lime 96 



Ammonia, (and most probably phosphoric acid united to the 

 ammonia), water, and common mucilage of urine, which 

 were not collected and weighed, by estimation 29 



300 

 I shall next relate some experiments, made in order to obtain the acid sublimate 

 of Scheele, or lithic acid of the new system of chemistry. 100 grs. of an urinary 

 concretion, which had been previously found to contain principally the above 



