166 
Anahjses of the Ashes of Phxnts. 
further and stronger lieating a further loss of • 08 was produced. 
The covered crucible was now introduced into a furnace and 
strongly heated ; the materials were fused into a transparent 
liquid and kept in that state for 1 0 minutes ; on cooling, the 
weight was found to be undiminished. The total loss of weight 
in the experiment was, therefore, 23 '98; the loss which should 
occur from the water in the phosphate 24 • 65 : so that in point of 
fact the diminution of weight was not quite so great as it should 
have been from the known proportion of water in the salt used. 
We considered this slight difference due to error in the experi- 
ment, which we did not think it necessary to repeat. 
Phosphates containing two atoms of fixed base with one of 
water are not therefore capable of decomposing a chloride at a 
high temperature. It was considered necessary to extend the 
experiment to a salt of this composition, but in which the basic 
water is replaced by ammonia, that is, the ammonio-phosphate of 
magnesia (2 Mg O, NH4 O, PO5 ).. This salt is generally 
believed to exist in all seeds, and from its composition we were 
led to believe that it might with chloride of sodium afford more 
affirmative results than the ordinary phosphate. 
18*84 grains of ammonio-phosphate of magnesia were heated 
to redness ; it lost 8 • 43 grains. 
34*14 grains of the same phosphate and 38*04 grains of 
common salt were heated together over a gas-lamp; the mixture 
lost 27 • 14 grains. 
Introduced into a furnace and perfectly fused, a further dimi- 
nution of 0'45 occurred, inaking the entire loss 27 * 59. 
Had the loss of weight been confined to the ammonio-mag- 
nesian phosphate, it would have been only 15*28 ; so that a very 
considerable dissipation of chlorine had here occurred, in all pro- 
bability going off" in the form of sal-ammoniac. 
It may, however, well be doubted whether the ammonio-phos- 
phate of magnesia is likely to occasion a loss of chlorine in the 
burning of plants for ash analysis, since from its ready decom- 
position by heat it is most probably destroyed long before the 
organic matter of the plant has been sufficiently removed to 
allow of contact between the salts enveloped in it. There is still 
another class of phosphates to examine, in reference to their 
action on the alkaline chlorides, namely, the phosphates with one 
equivalent of fixed base and one or more of water, like the bi- 
phosphate of soda : — 
6*41 grains of cr3stallized microcosmic salt (IIO, NH4 O, 
Na O, PO5 -f8 HO) were heated, and lost 3-29 grains, or 51 -32 
per cent. (The thecn-etical loss of the salt is 51 -03.) 
26 '40 grains of the microcosmic salt were mixed with. 36*62 
