36 THE ROYAL SOCIETY OF CANADA 



phosphoric acid, presumably the result of the hydrolysis of the nucleo- 

 and phosphorproteins of the meat used in its manufacture. The 

 precipitation of ammonium magnesium phosphate in cultures evi- 

 dently resulted from a combination of this phosphoric acid with the 

 ammonia produced by bacterial action and the magnesium contained 

 in the sea-water. Dr. Hodge kindly examined some of the precipi- 

 tates from a mineralogical standpoint and reported their exact agree- 

 ment in crystalline form with the mineral described by Maclvor under 

 the name "Hannayite."^ This appears to be the first record of the 

 artificial production of this mineral, but I have found that crystals 

 of the same form can be obtained by adding dilute ammonia gradually 

 to a dilute solution of MgNH4P04 -81120 in acid. The composition of 

 the mineral according to Maclvor is Mg2H2(P04)2-MgH2(NH4)2 (P04)2 

 -1-8H20.^ I am hoping to determine whether this is true of the salt 

 precipitated by bacterial agency and by the chemical method de- 

 scribed.^ 



In this connection it is worthy of note that the formation of crys- 

 tals of ammonium magnesium phosphate, having the crystalline form 

 of the mineral "Struvite," in artificial cultures of micro-organisms, 

 has been previously recorded.^ This mineral has been found by 

 Maclvor to have the composition Mg-(NH4)2(P04) + 12H20, and it is 

 entirely different in crystalline form to Hannayite. No crystals of 

 the form of Struvite have been found in any of the cultures in the 

 course of this work. 



The geological significance of the precipitation of this substance 

 from organic matter in sea-water under the influence of bacteria is 

 probably limited in the same way as that of the bacterial production 

 of calcium carbonate. Its production in the open sea would probably 

 depend on much the same conditions; that is to say it would be 

 expected to occur only where a mass of decomposing organic material 

 was giving rise to a local production of large quantities of ammonia 

 and phosphoric acid. It would seem to be of some interest from the 

 geological standpoint inasmuch as it suggests a means whereby the 

 phosphoric acid combined in the soft parts of plants and animals may 

 be thrown out of solution when they decompose and thereby contribute 



1 Maclvor. Ch. News. 65. 215. 1887. 



2 Chemical analysis of these salts, carried out since this paper was written, 

 shows them both to possess a composition approximating nearly to the formula 

 Mg. NH4P04-7 H2O. It is probable that this compound is the predominating one 

 in Hannayite and determines the crystalline form. Maclvor's analytical figures 

 indicate a mixture of combinations of ammonium, magnesium and phosphoric acid. 



3 Robinson. Camb. Phil. Soc, May 20th, 1889, and Solly. Minn. Mag., 8, 279, 

 1889 (quoted by Dana in his "System of Mineralogy"). 



