Austin — Double Anunonium Phosjphates in Analysis. 157 



duced by ammonium pliosphate (in only moderate excess) and 

 washed with a one per cent solution of the precipitant and alco- 

 hol has the ideal constitution of the double phosphate and 

 leaves upon ignition the pyrophosphate. 



From the standpoint of theory it is difficult to see why the 

 ammonium phosphate should be more effective in producing 

 the normal ammonium double salt than is hydrogen ammonium 

 sodium phosphate in amount sufficient to supply the ammo- 

 nium equivalent, or than a mixture of the equivalent amount 

 of any soluble phosphate in association with enough ammonium 

 salt to supply the same amount of the ammonium radical or 



ion. Whether the conversion of the tribasic phosphate of the 



II 

 type E-gP^Og to the double ammonium phosphate of the typo 



II • 

 (NHJRPO^ be viewed either as dependent upon the inter- 

 action according to mass of reagents assembled, or from the 

 point of view of the ion theory,'^ the action of a solution of 

 ammonium phosphate should not differ much from that of 

 equivalent amounts of other ammonium salt and soluble phos- 

 phate. My own experience with the double ammonium zinc 

 phosphate confirms this view.f In the following table are 

 reproduced from my former paper the data of certain experi- 

 ments bearing upon this point. 



ZnsPaOT 

 corre- 

 sponding 

 to ZnS04. 

 Taken, 

 grm. 



(1) 0-6355 



(2) 0-6355 



(3) 0-6355 



(4) 0-6355 



(5) 0-6355 



(9) 0-6355 



(10) 0-6355 



(11) 0-6355 



(12) 0-6355 



(13) 0-6355 



(14) 0-6367 



*Gooch and Austin, this Journal, vi, 233; Boettger, Ber. Chem. Gesell., 

 xxxiii, 1019. 



f This Journal, viii, 210. 



Am. Jour. Sci. — Fourth Series, Vol. XIY, No. 80. — August, 1902. 

 11 





Error in 



En-or 



Zinc 







Time 





terms 



in terms 



left 







of 





of 



of 



in the 







stand- 



Found. 



ZnaPsOr. 



Zinc. 



filtrate. 



(NH4)3P04. 



NH4CI 



.. ing. 



grm. 



grm. 



grm. 

 A 

 0-0060- 



grm. 



grm. 



grm. 



hours. 



0-6206 



0-0149- 



trace 



3-13 





H 



0-6254 



0-0101- 



0040- 



trace 



313 







16 



0-6300 



0-0055- 



0-0022- 

 B 



trace 



3-13 



HNaNH4P0 



.4H2O 



grm. 



h 



16 



0-6271 



0-0084- 



0-0034- 



trace 



4-47 



0-5 



1 



0-6256 



0-0099- 



0-0040- 



none 



4-47 



0-5 



20 



0-6335 



0-0020- 



c 



0-0008- 



none 



4-47 



10 



16 



0-6381 



0-0026 + 



0-0010 + 



none 



4-47 



20 



i 



0-6379 



0-0024 + 



0-0009 + 



none 



4-47 



20 



2 



0-6386 



0-0031 + 



0-0012 + 



none 



4-47 



20 



i 



0-6393 



0-0038 + 



0-0014 + 



none 



4-47 



20 



i 



0-6355 



0-0012 + 



0-0005 + 



none 



4-47 



30 



16 



