55 



lium sulphate, turbidity will be produced and finally some flocculi will 

 be deposited. Under the same condition solutions of magnesium sul- 

 phate, whether highly or moderately diluted, will remain perfectly clear. 



It is seen, therefore, that there is a fundamental difference between 

 beryllium and magnesium salts in their behavior to phosj)horic acid — a 

 difference which amply accounts for the fact that beryllium salts can 

 not replace magnesium salts, as far as the process of the assimilation 

 of phosphoric acid is concerned. In this resi^ect magnesium is unri- 

 valed even by the most closely related elements. With the properties 

 of easy dissociation of the salts and its character as only a weak base, 

 magnesia unites a moderate solubility of the secondary phosphate not 

 found with any other related base. Although beryllium oxid is also a 

 weak base, the fact that it is much more inclined than magnesia to 

 yield an insoluble phosphate renders it unsuitable for the function 

 mentioned. 



As to the rarer elements it may still be questioned whether there may 

 not exist among them some that could physiologically replace magne- 

 sium or calcium. The experiments with cerium and lanthanium showed 

 no evidence in favor of that view, these salts killing algae in a solution 

 of 0.1 per cent. Thorium sulphate is not so injurious, but no further 

 studies as to whether it can be utilized for any physiological function 

 have been made, nor have any experiments been made with yttrium, 

 niobium, or some other rare elements. 



IMPORTANCE OF LIME SALTS FOR ANIMALS. 



In animals lime salts are necessary not simply for the formation of 

 the bones, but also for every part of the body, and they are required 

 for the lowest forms as well as for the higher animals. 



The action of the heart is above all most intimately connected with 

 the presence of lime salts. Thus, a frog's heart will soon stop even in 

 a physiologic salt solution (0.6 per cent sodium chloride), but will con- 

 tinue to beat whea some ash of blood is dissolved in the same solution. 

 Einger has shown that a good circulating fluid for the heart may be 

 compounded by preparing a mixture of such salts as normally occur in 

 the blood. In such a solution the isolated frog's heart will beat almost 

 as long as it would in defibrinated blood. Halliburton^ says: "The 

 necessity for lime salts is especially great. In fact, the close adhesion 

 of proteids generally with small quantities of mineral matter is rather 

 suggestive of combination than mere mixture. Lime salts adhere 

 especially closely and in fact seem indispensable for many of the func- 

 tions of the body, of which the beating of the heart and the contraction 

 of skeletal muscle are good examples. Blood from which the salts 

 have been removed keeps the heart going, but the tracing is abnormal, 

 resembling that produced by a weak solution of a lime salt. It is in 



Chem. Physiol., 1891, London, p. 256. 



