156 
Analifscs of the Ashes of Plants. 
ash. Microcosniic salt was heated to redness, and the resulting 
metaphosphate mixed with sulphate of potash : — 
Metaphosphate of soda (Na O P Oj) . . 23*57 grains. 
Sulphate of potash . . . . . 32 * 06 
53-63 
The materials were strongly fused till they became liquid. 
On cooling, the weight was 55 • 54. We considered this loss of 
• 09 evidently due to error of experiment, and did not think it 
necessary to repeat the trial. It is therefore plain that a phos- 
phate with one equivalent of fixed base is equally unable with a 
pyrophosphate to drive off sulphuric acid from an ash. And we 
may at once decide that there is no reason for fearing a loss of 
sulphuric acid in any non-silicious ashes. 
But is the whole sulphur of plants necessarily present in them 
as sulphuric acid ? or, if not, does it follow that it should become 
sulphuric acid in the burning ? Our knowledge of the compo- 
sition of the nitrogenous compounds of plants would lead us to 
answer the first question in the negative. The gluten, albumen, 
&c. of plants is known to contain sulphur — if not quasi sulphur, 
still in some other form than as sulphuric acid ; and the experi- 
ments we are about to bring forward prove that the sulphur is 
not really retained in the ash, but that a very large proportion of 
it (in some cases amounting to two-thirds of the whole quantity) 
is dissipated in the burning. 
The following experiments prove that slight differences in the 
method of burning a plant give very dissimilar quantities of sul- 
phuric acid in the ash. 
Of course, a non-silicious vegetable was employed, and, as a 
matter of convenience, turnip-seed was chosen for experiment. 
One thousand grains of turnip-seed were burnt in a large platinum 
dish in the usual way, a temperature scarcely reaching dull red- 
ness being employed ; the asli was dissolved in nitric acid, and 
the sulpliuric acid estimated as sulphate of barytes in the usual 
way : — 
Sulphuric acid in the 1000 grains of turnip-seed . 2*944 
Three other experiments were made on equal quantities of the 
same seed, the temperature, the length of time in burning, &c. 
being as far as possible the same in all. The results were as 
follow : — 
2nd experiment, sulphuric acid in 1000 grains of 
turnip-sccd ..... 2*710 
3rd „ „ „ ,, 2 -900 
4th „ „ „ „ 3*460 
