BULLETIN OF THE BUSSEY INSTITUTION. 195 
lost 0.87% of moisture on being dried at 212°, and No. IV. lost 0.51%. 
Sample No. I., obtained from a soapboiler’s stock, gave off 24% of 
moisture. 
For the estimation of potash, five grammes or thereabouts of the ashes 
were digested for half an hour or more, with concentrated nitric acid in a 
covered beaker. The liquor was diluted with water, thrown upon a filter, 
and the insoluble sand and charcoal carefully washed with hot water. 
The filtrate was evaporated nearly to dryness in a small porcelain dish, 
and thoroughly mixed with a solution of ferric nitrate. ‘The evaporation 
was then pushed to dryness, and the capsule placed upon a wire tripod in 
a small iron pot which was heated in accordance with Deville’s direc- 
tions,* until the excess of nitrate of iron was completely decomposed. 
The residue was treated with hot water, filtered, and the filtrate and 
wash-water, acidulated with chlorhydric acid, were evaporated to dry- 
ness in g porcelain dish. The dry residue was drenched with strong 
chlorhydric acid, and the contents of the dish were again evaporated to 
dryness to destroy the nitric acid, this operation being repeated until no 
trace of chlorine could be detected, by means of iodo-starch paper, in the 
fumes arising from the dish. The residue, freed from nitrates, was acid- 
ulated with chlorhydric acid, and treated with as small a quantity of: 
highly dilute chloride of barium solution as was sufficient to precipitate 
all the sulphurie acid, and in the filtrate from the sulphate of baryta the 
potassium was determined, as chloroplatinate, by Stohmann’s process, as 
described in Fresenius’s Zeitschrift ftir analytische Chemie, 5. 307.+ 
For estimating the phosphoric acid, the process: ordinarily employed 
was as follows: Five grammes or so of the ashes were digested for 
half an hour or more with strong chlorhydric acid in a covered beaker, 
and the mixture was evaporated to absolute dryness upon a water bath © 
to render the silica insoluble. The dry residue, which contained sand 
and charcoal, as well as silica, was moistened with strong chlorhydric acid 
in the usual way, then treated with hot water, filtered, and washed. In 
the filtrate, phosphate of iron was thrown down by means of ammonia 
* Fresenius’s “ Quantitative Analysis,” New York edition of 1871, p. 852, § 38. 
+ Considerable experience with Stohmann’s process enables me to say that 
it succeeds well in practised hands. It is of the first importance, however, that 
the least possible excess of chloride of barium shall be used in precipitating the 
sulphuric acid; for, under the conditions which obtain in an actual analysis, it 
may happen that the union of chloride of barium and bichloride of platinum 
to form the soluble chloroplatinate of barium, upon which the success of the 
operation depends, will be incomplete, no matter how large an excess of free 
chloride of platinum is present. In that event, the chloroplatinate of potassium 
is contaminated with crystals of hydrated chloride of barium insoluble in alco- 
hol, which, being somewhat lighter than the true precipitate, collect upon its 
surface as a white, slimy powder. I have noticed that beginners almost invari- 
ably encounter this difficulty, and that it can usually be overcome by the exer- 
cise of special care in adding the chloride of barium. . 
