404 WSchmidi’s Process for the Determination of Nitrogen. 
Another experiment conducted in the same manner, with the 
exception that the pyrophosphate of magnesia was converted into 
the tribasic condition, by fusion with carbonate of soda, gave 8°35 
per cent. as the loss. The loss of phosphoric acid when the so- 
lution was acidified with sulphuric acid instead of hydrochloric 
acid was greater, probably owing to the higher degree of heat re- 
quired to volatilize that acid. There was no perceptible difference 
between the action of hydrochloric and nitric acids. Phosphate 
of soda was completely converted into the sulphate of the same, 
by three evaporations with sul phuric acid and water. Phosphates 
of alumina, iron, lime and magnesia were not perfectly converted 
into sul phates even bya dozen successive evaporations. Phos 
phoric acid does not seem shes be more volatile in the vapor of 4 
cohol than in that of wat 
hese experiments serve to show that the ordinary methods of 
analysis are not applicable to the analysis of phosphates which 
must be dissolved in acid by the aid of heat. In the ordinary 
evaporations to separate silica by rendering it insoluble, a very 
considerable loss of this acid is occasioned. ‘The estimated quan- 
tity of phosphoric acid in ashes, &c., must probably in many 
cases be much too low, owing to this loss from volatilization, and 
we may believe that for this reason many analyses must be re- 
garded. as almost valueless with respect to the amount of phos- 
phoric acid which "they indicate. 
2. On Schmidi’s Process for the Determination of Nitrogen. 
Chemists engaged in organic analysis have long felt the want 
of a quick and accurate process, for the determination of nitrogen. 
Several objections may be offered to the method of Messrs. Will 
and Varrentrapp—in following which, the substance to be analyzed 
is burned in contact with soda-lime, the ammonia formed is pass- 
ed into a solution of hydrochloric acid gas, and after evaporation 
pea as ammonio-chlorid of platinum. The more import- 
of these arises from the solubility of the platinum salt, and the 
time required for the evaporation, drying, weighing, &c. In Lie- 
big’s report for 1847 and ’48, mention is made of several new meth- 
ods for the pte am of nitrogen. ' Of these that of Schmidt 
attracted my attention and I was led to make some experiments 
upon it. He al the substance as in the Will and Varrentrapp 
process, and passes the ammonia formed into a solution of one 
] 
] 
r 
ta 
is belsalanad by equiva alents. In experimentin on this process, 
‘burned carefully crystallized jin ar of igo which ie 
be a proved pure by ee Pxperiment and I obtained results 
