196 



Gooch and Austin — Constitution of the 



that the magnesium mixture was introduced into the ammonia- 

 cal solution of the phosphate drop by drop from a burette. 

 The precipitations in A, B and C were proved to be practically 

 complete ; for by treatment of the filtrates with more mag- 

 nesia mixture and standing, no more than a trace— 0*0001 grm. 

 at the most— of the phosphate was found. The ignited resi- 

 dues never contained more than a mere trace of chlorine. 









Table VI 











Mg 2 P 2 7 

 correspond- 

 ing to 

 HNa 2 P0 4 

 taken. 



Mg 2 P 2 7 

 found. 



Error 

 in terms 



of 

 Mg 2 P 2 7 



Error in 



terms of 



P. 



Volume. 



NH 4 C1 

 in mag- 

 nesia 

 mix- 

 ture. 



NH 4 C1 

 added. 



MgCl 2 . 

 6H 2 in 

 magnesia 

 mixture. 



grm. 



grm. 



grm. 



grm. 



cm 3 . 



grm. 



grm. 



grm. 



( 1) 0-8615 

 ( 2) 0-8615 

 ( 3) 0-8615 

 ( 4) 0-8615 



0-8613 

 0-8615 

 0-8602 

 0-8561 



-00002 



o-oooo 



-0-0013 

 -00054 



-0-00005 



o-ooooo 



— 0-00036 

 -0-00151 



150 

 200 

 200 

 BOO 



1-68 



u 



20 

 20 

 60 



33 

 it 



( 5) 0-0852 

 ( 6) 0-0852 

 ( 7) 0-0852 

 ( 8) 0-0852 

 ( 9) 0-0852 



0-0862 

 0-0866 

 0-0847 

 0-0830 

 0-0811 



+ 0-0010 

 + 0-0014 

 -0-0005 

 -0-0022 

 -0-0041 



+ 0-00028 

 + 0-00039 

 — 0-00014 

 —0-00062 

 -0-00115 



100 

 100 

 200 

 200 

 300 



0'28 



u 

 (( 

 (( 



"20" 

 20 

 60 



0-55 



it 

 u 



u 



(10) 0-8111 



(11) 0-8615 



(12) 0-8615 



(13) 0-8615 



08114 

 0-8613 

 0-8578 

 0-8487 



+ 00003 

 -0-0002 

 -0-0037 

 -00128 



B 

 + 0-00008 

 -0-00006 

 -0-00103 

 -0-00358 



150,100 

 150,100 

 200,100 

 200,100 



1-68 



::|2o 



..,60 



3-3 



a 

 u 



(( 



(14) 0-0852 



(15) 0-0852 



(16) 00852 



(17) 0-0852 



0-0857 

 0-0656 

 0-0853 

 0-0819 



+ 0-0003 

 + 0-0004 

 + 0-0001 

 -0-0033 



+ 000008 

 + 0-00011 

 + 0-00003 

 -0-00092 



100,100 

 100,100 

 150,100 

 200,100 



28 



a 

 u 

 u 



10~,'" 

 10,10 

 20,20 



0'55 



u 



(18) 0-8111 



(19) 0-8111 



0-8071 

 0-8052 



-0-0040 

 -0-0059 



C 

 -000112 

 -0-00165 



120 

 120 



1-4 

 1-4 



.... 



2-75 

 2-75 



While the results are not entirely regular, the tendency of 

 the ammonium salt to produce errors of deficiency in propor- 

 tion to its amount is plain if we compare among themselves 

 the experiments of A upon similar amounts of phosphate, and 

 then those of B upon similar amounts of phosphate among 

 themselves; and by a comparison of corresponding results in 

 A and B it is clearly shown that the presence of an excess of 

 magnesia mixture tends to counteract more or less completely 

 errors of deficiency due to the action of the ammonium chlor- 

 ide. These facts are quite in harmony with the hypothesis 

 that the ammonium salt tends to produce an ammonium mag- 

 nesium phosphate richer in ammonia and phosphoric acid and 

 poorer in magnesia than the normal salt ]STH 4 MgP0 4 ; for, 



