i;6 Chemicjl RfffarchiS Inij the Nature of the RiAds. 



chara£ler is analogous to the fcrnientcfcibic vegetable acids, and more or lefs to the oxalic 

 acid ; and that, on the contrary, the ailimal acid or phofphoric acid ceafes to be formed, and 

 to' unite with tl\e animal calcareous earth ; whence they arc deprived of the principle of 

 their folidity. This is the theory of Citizen Bonhommc. 



In order to eftablifli this doctrine upon prctife experiments, it was rcquifite to analyfc 

 rachitic bones comparatively with thofc of healthy individuals of the fame age ; und as it 

 is ki.ov.n that the urine of rachitic fiibjcCls ilcpofits a great quantity of a fubftance of fparing 

 folubility and earthy appearance, it would have been advantageous to have joitied a com- 

 plete analyfis of this urine and its fediment. 



Citizen Bonhomme not being provided with the means fufTicicnt to make thefe analyfes, 

 and b;.ing befides of .opinion that fucli rachitic bones as are deftroyed by this malady exift 

 in a progrelTive (late of change, which might render their analyfis fcarccly fufceptible of 

 comparifon,. limited himfclf to a coUeftion of fome of the mod remarkable phenomena of the 

 urine of the aged, the adult, and infants in the healthy (late, of infants in the rachitic ftate, 

 and of patients after the perfe£l cure of this diforder. From thefe obfervatlons he has 

 deduced feveral important rcfults. 



It is known that when the urine contains difengagcd phofphoric acid, as happens to aged 

 individuals, and in fomc peculiar circumftances of the fydem, if lime water be poured in 

 ihere is a fpeedy dcpofition of calcareous phofphate. It is alfo known, that when a folution 

 of the nitrate of mercury is poured to the frelh urine of adults, a rofc-colourcd precipitate 

 is formed, which is a phofphate of mercury produced by the decompofition of the phofphates 

 contained in the urine. Thefe two proofs are therefore extremely proper to afcertain the pre- 

 fcnce of phofphoric acid, whether free or combined, in a fluid which in its natural ftate 

 contains a remarkable proportion. Befides this principle, the urine depofits more or lefs of 

 fediment, cither gelatinous or of an eftrthy appearance ; and laftly, by evaporation, a fapo- 

 naceous and faline extracl, in greater or lefs abundance, is obtained by evaporation. By 

 means of thefe four methods of examination, the author has afcertained the following fa£ls : 



1. In the healthy ftate, the fediment naturally depofitcd by urine is almoft totally gelati- 

 nous in the infant and the adult, and in the aged individual it is furcharged with an abun- 

 dant fediment of an earthy appearance fimilar to the earth of bones, which confequcntly is 

 calcareous phofphate. 



2. The quantity of brown faponaccous faline extract aftbrdcd by evaporation is greater 

 in proportion to the age. . 



3. The prefence of difengaged phofphoric acid, as flicwn by lime water, is none in the 

 urine of infants, fcarcely perceptible in that of adults, but very remarkable in that of old 

 men. For tvi'O ounces of this laft urine afforded by this means ten grains of phofphate of 

 lime. 



4. The decompofition of the phofphates by nitrate of mercury is not feen in the urine of 

 infants ; an abundant precipitate of a light rofe-colour is produced in this way from the 

 urine of adults ; and in that of old men this precipitate is always of a grey colour, and very 

 abundant. 



Hence Citizen Bonhommc concludes, that the phofphoric acid, whetlier at liberty or 

 combined, does exift in the urine of healthy individuals in proportion to the deftruc- 

 tiun of the folids by age, and that it increafes with the age. 



With 



