757 



known to live upon urea, and nitromonas would then merely possess 

 the advantage over these bacteria of being able to manufacture for 

 itself the urea upon which it lived. 



The chemical changes induced by the nitromonas differ materially 

 from tliose which occur with chlorophyll. In the action of chlorophyll 

 carbon dioxide is decomposed with the aid of the sun's energy, oxygen 

 is liberated, and the carbon unites with hydrogen and oxygen to form 

 carbohydrates indirectly. But, as indicated by Wiuogradsky's experi- 

 ments and inferences, the uitro-bacteria instead of decomposing carbon 

 dioxide ;ind setting its oxygen free, effects its union with ammonia and 

 the formation of amide-like compounds; they also make use of the 

 oxygen of the air to oxidize the nitrogen to nitrous and nitric acids; 

 and finally the energy required for their work is supplied from the 

 oxidation which they bring about. 



In the last article at hand Winogradsky discusses the methods of 

 culture of the nitrobacteria, and especially a culture medium of which 

 hydrated silica is an essential constituent, and in which mineral salts 

 but no organic matter are used. This serves its purpose excellently 

 and has the special advantage that few other organisms than the 

 nitromonas grow in it. 



The water-soluble phosphoric acid compounds in superphosphates, J. 

 Stoklasa {Landiv. Veraiwhs^Stationen, 38, pp. 401-410, continued from 

 Ibid., p. 197; see Experiment Station Record, Vol. II, p. 611). 



Action of dicalcic plwupliate. — Working with pure material, an inter- 

 esting occurrence was noticed in the formation of monocalcic phos- 

 l)hate by the action of a solution of free phosphoric acid on dicalcic 

 phosphate. The phosphoric acid unites with the dicalcic phosphate 

 until the solution is com [)letely saturated, t. <?. contains practically 1 

 gram of the salt to 200 grams of water, as stated in the previous 

 paper. After saturation has been reached the dicalcic phosphate 

 remains unacted upon by the free acid. 



According toEeichart,* Boedecker,t and others, if dicalcic phosphate 

 is boiled with water, monocalcic phosphate is formed. ErlenmayerJ 

 states that after 24 hours' boiling only a weak reaction was noticed with 

 litmus paper. The author heated 2.5 grams of dicalcic phosphate with 

 500 c.c. water; at the end of 3G hours only a very weak reaction was 

 noticed with litmus tincture. Analyses of the watery solution, 0.03-0.05 

 per cent of phosphoric acid which had been dissolved from the dicalcic 

 salt. 



To study the action ot dicalcic upon monocalcic phosphate, the two 

 were mixed in the proportions of 5, 2.5, and 1 gram, respectively of 

 diphosphate to 5 grams of monophosphate in 2,000 c. c. water. After 

 standing for mouths, with frequent shaking, the per ceutage of free 



* Archiv. Pharni., 3, 2, p. 236. 

 t Auual. Phann., 69, p. 206. 



X Sitzuugsberichto d. K. B. Akad. d. Wiss., 1872, p. 269. 

 28519— No. 12 5 



