II8 



1$. Fcltlyaina. 



In order to decide this question, 25 g. bone dust^^ as well as equivalent 

 doses of bone ash-^ were left with frequent shaking in 2.5 litres of water as 

 well as of \% potassium carbonate solution for 42- months'^^ at room 

 temperature ; in one case 5 c.c. of neutral chloroform were added to prevent 

 any bacterial action, while in the others chloroform was excluded. 

 Phosphoric acid had indeed after that time passed into solution ; therefore 

 potassium phosphate must have been formed. The quantitative determina- 

 tions in one litre of the liquid gave the following results : 



I 



II 

 III 

 IV 

 V 

 VI 

 VII 

 VIII 



Bone dust in water 



Bone ash „ , 



Bone dust in water with chloroform... 



Bone ash „ „ ,> „ 



Bone dust in 1% K2CO3 solution ... 



Bone ash „ „ „ „ 



Bone dust in 10/0 K:iCOa solution with chloroform 



Bone ash „ „ „ „ „ „ 



Milligr. PaOa dissolved in one litre. 



After I month. 



7-65 

 0.57 

 5-29 

 0.19 



45-91 

 8.16 



44-51 

 542 



After 2 months 



0.51 

 47.82 



8.99 

 4578 



6.89O 



After 4^ months. 



12.66 



0.71 



7.46 



0.64 

 68.95 



56.04 

 8.42 



These numbers show that the bacteria play indeed a role catising: 

 solution of phosphoric acid from bone dust (compare I with III). In the 

 presence of bacteria (I), the amount of dissolved phosphoric acid had 

 increased by yo%^^ after.'4Y months over the amount of dissolved phosphoric 

 acid in the presence of chloroform. 



When we further^ compare II and IV, we find that the absence of 

 chloroform has not led to any notable increase of the dissolved phosphoric 



i). The bone dust was the same as that applied in the above fourth experiment. 



2). The bone ash was freshly prepared by igniting 25 g. bone dust mertioi ej. 



3). From December 26, 1905 to May 11, 1906. 



4). This figure is smaller than the corresponding figure of VI (8.99), which may be due to the 



gradual decomposition of chloroform by the potassium carbonate, whereby jx):assium chloride an-l 

 fOtassium formate result. 



5). 7.46:12.66=100:170. 



