973 



It was, tlierefore, exceedingly striking that Dr. H. Hecht (leader 

 of Prof. M. Dittkich's Laboratory at Heidelberg) achieved results 

 widely different from the four above-mentioned cases. 



Leaving out of consideration the substances traced for the first 

 time in small quantities, the high amount of magnesium oxide is 

 most conspicuous. Pi-es had not found any of it, Abel i.86' , and 

 Thoms only 0.34 "/o- An increase to lJ.64''/„ coincided with a 

 decrease of calcium oxide to 16.75 7o- Since microscopical examina- 

 tion had already established that the secretions were to be considered 

 as a mixture of two substances, we could hardly conclude that we 

 had to do with a double salt viz. a calcium-magnesiumphosphate. 

 Moreover it appeared from the calculation that the composition did 

 not correspond with a similar compound — H^CaMg(PO*)' -|- 4H''0 — 

 which would require 43.22 P'0% 17.08 CaO, 12.28 MgO, 27.42 H'O. 



The presence of a mechanical mixture of a calcium- and a mag- 

 nesiumphosphate or of a calcium- and a calciummagnesiumphosphate 

 seemed to me much more plausible. On the assumption that the 

 concietions examined by us, contain the calcium-phosphate demon- 

 strated by Ples, Abel and Thoms, the magnesiumphosphate may be 

 computed from the analj'sis. When subtracting the 0.53 SiO*, 0.05 

 APO», 0.07 Fe'O», 0.05 CO' present, and the 0.06 CaO required for 

 the combination of the CO' the remainder will be in percentages : 



