410 MINERAL CONSTITUENTS OF THE ANIMAL BODY. 



ashes of vegetable and animal substances; and notwithstanding 

 this, we are struck with the great accuracy of many of the earlier 

 analyses of ashes, although from the methods then employed we 

 should have expected that their calculations would of necessity 

 have yielded a minus in the one case and a plus in the other. 



We will here only refer to the fact that few observers before 

 Rose had observed that alkaline as well as earthy salts were con- 

 tained in the insoluble portion of the ash, and that, conversely, the 

 presence of carbonate and phosphate of lime in the aqueous extract 

 of the ash had been very generally overlooked, while the very 

 imperfect precipitation of the pyrophosphate of magnesia by am- 

 monia was equally disregarded. The imperfect manner in which 

 even the simplest relations of this nature have been investigated, 

 is made apparent by the doubts entertained by Berzelius himself, 

 in reference to the composition he had ascribed to bone-earth, 

 which were verified by the investigations of Rose and W. Heintz,* 

 by whom it was definitely proved that the phosphate of lime in 

 the bones is represented by 3CaO.PO 5 , and not as Berzelius had 

 given it, by 8CaO.3PO 5 . The difficulty of conducting exact 

 analyses of ash was, however, mainly increased by the deficiency of 

 any clear and comparatively simple method of separating phosphoric 

 acid from its proteus-like salts, and determining it quantitatively. 

 But this cause of difficulty has likewise been recently obviated by 

 H. Rose'sf method of thoroughly separating the acids from their 

 bases by means of mercury and nitric acid. 



When we consider these facts in reference to the analysis of the 

 ash, we shall readily arrive at the conclusion, (without, however, 

 wishing to animadvert upon those analysts who have engaged in 

 laborious examinations of the ash of animal bodies,) that most of 

 these analyses should be used with great caution, and that physio- 

 logical conclusions should not be too readily drawn from them. It 

 has, unfortunately too often happened that the empirical results of 

 analyses of the ash have been applied to the explanation of physio- 

 logical processes without due consideration, and thus the import- 

 ance and efficiency of the mineral salts of the animal body have 

 been extolled before we had any accurate knowledge of the sub- 

 stances themselves ; and the most rigorous scepticism in reference 

 to medical experiments has not unfrequently been associated with 

 a blind confidence in the least reliable of the numerical determina- 

 tions of chemists. 



* Ber. der Ak. d. Wiss. z. Berlin, Febr. 1849, S. 50-53. 

 t Ibid. S. 42-45. 



