802 ORGANIC 
crystalline precipitate if any magnesia were 
still contained in the liquid. 
k. A portion of the original liquid (6) is 
acidulated with a drop or two of hydrochloric 
acid ; if sulphuric or phosphoric acid have been 
detected (by ¢ and e), chloride of barium in slight 
excess is added, the solution filtered, heated, 
and precipitated by a mixture of caustic and car- 
bonate of ammonia ; it is again filtered, the 
liquid evaporated to dryness and ignited, the 
residue dissolved in alcohol, and sufficient alco- 
holic solution of bichloride of platinum added 
to eceene a yellow liquid: a yellow precipitate 
indicates potash. If no sulphuric or phosphoric 
acid be present, the use of the chloride of ba- 
rium and ammonia will become unnecessary. 
l.. Decant the yellow solution just obtained 
(k) from the precipitate, if there be any, and 
allow it to evaporate spontaneously or at a very 
gentle heat. If soda be present, !ong prismatic 
yellow needles of the double chloride of pla- 
tinum and sodium form. This is the best test 
of the presence of soda. The yellow tint which 
its salts communicate to the exterior flame of 
the blowpipe, when heated on a platinum wire, 
has been proposed, but this is by no means an 
unequivocal appearance. Almost all the animal 
fluids contain soda in the form of common salt. 
B m. The insoluble fixed residue (B) may 
contain phosphates and carbonates of lime and 
magnesia, as well as phosphate and oxide of 
iron, and traces of silica. The residue is treated 
with nitric acid, by which every thing but the 
silica is dissolved. Carbonic acid, if present, 
is manifested by effervescence. 
n. The solution is diluted and filtered; to 
one portion ammonia free from carbonic aeid 
is added ; if phosphoric acid be present, a preci- 
pitate occurs whilst the liquid still remains 
acid; under these circumstances ammonia is 
added as long as the precipitate at first formed 
re-dissolves in the solution, still acid. Ifa solu- 
tion of acetate of lead, carefully dropped in, 
cause a white precipitate, soluble in nitric acid, 
and which if collected and dried fuses before 
the blowpipe into a semi-transparent bead, 
which assumes a crystalline structure on cool- 
ing, phosphoric acid is indicated by the phos- 
phate of lead thus obtained. 
o. Another portion of the acid liquid is neu- 
tralized by ammonia, and the precipitate, if any 
occur, re-dissolved by acetic acid. Ovxalate of 
ammonia shews lime by the formation of a 
white precipitate. 
p- To the liquid filtered from the oxalate of 
lime carbonate of ammonia is added in slight 
excess; if the previous examination’ have 
shewn phosphoric acid to exist, a crystalline 
precipitate indicates the double phosphate of 
ammonia and magnesia. If no precipitate be 
thus obtained, boil the liquid, and the magnesia 
in solution falls as carbonate. 
g. Oxide of iron is detected instantly by 
adding a drop of solution of ferrocyanide of po- 
tassium to the acid solution: an immediate Prus- 
sian blue precipitate shews iron, if present. The 
precipitates obtained in the previous experi 
ments for lime and magnesia will, instead of 
being white have a more or less decided rusty 
ANALYSIS. 
brown tint, especially when dry, if iron form 
any considerable part of the matter examined. 
For the detection of iodine, lead, and the 
other bodies enumerated in the list of inorganic — 
substances for which we may occasionally have 
to look, the reader is referred to the followin 
directions for the quantitative estimation of the 
different compounds. ” 
Quantitative estimation. 
For the convenience of analysis our sa 
matter may be divided into two portions, one 
of which is employed for determining the acids, 
the other for the bases. The first portion 
enable us to ascertain the quantity of carboni 
and phosphoric acids, of chlorine, and of s1 
phuric acid. From the second portion w 
obtain the potash, soda, lime, magnesia, iro! 
and alumina, if, as rarely occurs, the latter b 
present. 
Other ingredients will usually be matter ¢ 
special examination ; the details of the meth 
to be pursued are subjoined. 
We begin by treating the salts to be 
mined with water (solution A). Nothing 
carbonates and phosphates of the earths 
thus remain undissolved (residue B). "4 
(A.) Carbonic acid.—The aqueous solution 
treated with lime-water, or with a mixture 
ammonia and nitrate of lime, as long 
precipitate is produced. If no phosphates 
present, this consists of carbonate of lin 
the solution is boiled—filtered, the p 
ignited, and after adding a few drops of str 
solution of carbonate of ammonia heated be 
redness and weighed, 100 grs. of carbonate 
lime indicate 44 of carbonic acid When ph 
phates are present, we proceed as follows + 
Phosphoric acid—The precipitate ob 
by lime-water, as thus directed, contains 
phosphoric acid that may be present. 
fore phosphates existed in our solution, the: 
cipitate, after its weight” has been ¢ 
ascertained, must be dissolved in nitrie 
and caustic ammonia (free from carboni¢ 
added in slight excess. The phosphe 
separates as a gelatinous precipitate of j 
phate of lime. It must be ignited am 
weight deducted from that of the mi: 
cipitate previously obtained ; the differen 
dicates the quantity of carbonate of lime: 
precipitated phosphate of lime contains 
per 100 of phosphoric acid. Phosphate oi 
dissolves in nitric, hydrochloric, or aceti 
without effervescence, and is thrown dow 
ammonia in a gelatinous form. The | 
phates and carbonates being thus 
the filtered solution is treated for, 
Hydrochloric acid— The quantity 0 
acid or of the chlorine it contains maj 
be determined by precipitating the 80 
pretty strongly acidulated with nitri 
means of nitrate of silver. The eh 
silver thus obtained is completely se 
ammonia, but resists the action of str 
acid even when boiling. The precipita 
be ignited; it should undergo fusi 
horny mass at a heat a little below 
Tt is now weighed; 100 parts indic 
chlorine. "1 
. 
PCIT 
— 
\ 
