368 
VARIOUS METHODS OF ANALYSING ASHES. 
amount of sulphuric acid estimated. The liquid filtered from the 
sulphate of baryta is mixed with an excess of ammonia, then set 
aside for some time, the separated phosphate of baryta collected 
on a filter, dried calcined and weighed, and calculated according 
to the above formula. The liquid filtered from the mixed barytic 
precipitates is used for the determination of the potash and soda ; it 
is freed by carbonate and caustic ammonia from baryta and other 
earths, evaporated to dryness, the ammonical salts dissipated, the 
residue dissolved in water and the potash determined by the chlo- 
ride of platinum ; the filtered liquid is examined for soda. A fourth 
weighed portion is mixed with oxalate of potash after acidification 
with nitric acid. When, as is generally the case, lime is present 
in the extract, the precipitate of oxalate of lime is heated to a 
faint red, and the lime calculated from the amount of the carbon- 
ate. The liquid filtered from the oxalate of lime is mixed with 
ammonia-phosphate of soda to precipitate the magnesia. 
III. This consists in examining the insoluble portion of the 
charcoal ash left in II. This insoluble residue is digested with 
muriatic acid, and evaporated to dryness to remove the silica, 
again dissolved in warm muriatic acid, the residual sand and sili- 
ca collected on a filter, the mixture dried, weighed, and the silica 
separated from the sand by solution in caustic potash. 
The filtered acid liquid is divided into two equal parts, the one 
half employed for the estimation of the potash and soda, the other 
for the determination of the earths, peroxide of iron and phosphoric 
acid, according to the following plan. The one half is heated to 
boiling in a glass flask, mixed with acetate of soda and some acetic 
acid : the resulting precipitate, consisting of perphosphate of iron 
and phosphate of alumina, or of the first only, is collected on a filter 
dried, calcined and weighed. To separate the peroxide of iron from 
the alumina, the weighed precipitate is dissolved in muriatic acid 
diluted with water, and heated to boiling for some time with the 
addition of caustic potash. The separated peroxide of iron is Col- 
lected upon a filter, and calculated for phosphate of iron according 
to the formula Fe + PO' ) proposed by Wackenroder. The alu- 
mina is precipitated from the filtered alkaline liquid by acetic acid 
as phosphate of alumina = ArW-f-PO 5 , dried, calcined and 
weighed. In this case we must not omit to examine the mixed 
precipitate obtained by acetate of soda for the presence of phos- 
