5G1 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. [January 14,187?. 
precipitate with excess of solution of potash, the fil¬ 
trate from which is unaffected by sulphide of ammo¬ 
nium.] If any zinc compound were present the fil¬ 
trate would retain it, and would give white sulphide 
of zinc on the addition of sulphide of ammonium. 
[§ Ten grains dissolved in water and nitrate of silver 
added in excess, give a precipitate which, when 
washed with water and afterwards with half an ounce 
of solution of ammonia and dried, weighs 12'5 grains.] 
The precipitate is, of course, iodide of silver, and the 
object of washing it with ammonia is to remove ad¬ 
hering traces of the cadmium salt. It should he re¬ 
membered that the precipitate is not absolutely in¬ 
soluble in ammonia. Since Cdl 2 is the formula of 
iodide of cadmium, it will yield 2 molecules of AgT. 
266 parts of iodide of cadmium give then 170 parts 
of iodide of silver; 10 grains will therefore yield, 
theoretically, 12’84 grains. 
Calcii Chloridum. — [§ It may be formed by neu¬ 
tralizing hydrochloric acid with carbonate of lime, 
adding a little solution of chlorinated lime and slaked 
lime to the solution, filtering, evaporating until it 
becomes solid, and finally drying the salt at about 
490°.] 
The object of this process is to remove from the 
salt ferric oxide and alumina, which are very com¬ 
monly present. When thus prepared, the product 
answers to the Pharmacopoeia test. [§ The aqueous 
solution is not precipitated by the addition of lime- 
water.] 
Calcis Carbonas prjecipitata.— Solutions of chlo¬ 
ride of calcium and carbonate of soda are mixed to¬ 
gether, the precipitate collected, well washed and 
dried at 212 Q :— 
CaC%+ Na 2 C0 3 = Ca C0 3 + 2NaCl. 
See Creta Prceparata. 
C alcis Hydras. —The operation of slaking lime is 
familiar to every one. In operating upon small 
quantities hot water is best. Slaked lime should 
not be exposed to the air for any length of time, as 
it absorbs carbonic anhydride, becoming converted 
into carbonate. 
Very pure lime, free from the alumina, iron, silica 
and alkaline chlorides commonly present in the or¬ 
dinary kind, is now prepared commercially from 
marble, and can be procured at a cheap rate. 
Calcis Phosphas. —Bone ash is digested in di¬ 
luted hydrochloric acid, and the filtered liquid mixed 
with solution of ammonia in slight excess. The pre¬ 
cipitated phosphate is to be thoroughly washed 'with 
hot water. Bone ash is composed of:— 
Ca s 2P0 4 
CaHP0 4 
CaCO s 
MgHP0 4 w 
CaF*. } tiaces - 
Tricalcic phosphate 
Monocalcic phosphate 
Calcic carbonate . . 
Magnesic phosphate 
Calcic fluoride . . 
Mixed with particles of carbonaceous matter. Wher 
treated with hydrochloric acid, all dissolve except tin 
particles of carbon and sandy matters that are gene 
rally present. On filtering the solution and adding 
ammonia, the chloride of calcium, which was formec 
by the solution of the carbonate, supplies calciun 
to the monocalcic phosphate, and thus a precipitate 
composed chiefly of Ca 3 2 P0 4 , is produced. For de 
tection of phosphate o± lime, see Bism. Subxitras. 
Calx. —See Calcis Hydras. 
Calx Chlorata. — [§ A product obtained by ex¬ 
posing slaked lime to the action of chlorine gas as 
long as the latter is absorbed. It possesses bleach¬ 
ing and disinfecting properties.] This compound is 
very commonly represented as a mixture of hypo¬ 
chlorite and chloride of calcium— 
2 CaO + 2 Cl 2 = Ca 2 CIO + CaCL. 
Hypochlorite. Chloride. 
Many of its characters, however, indicate that this 
view cannot be correct. Thus, it is not so soluble 
in water as it should be on such a supposition ; it is 
not particularly deliquescent, and yields but a small 
amount of chloride of calcium when treated with 
spirit. It is more probably a compound intermediate 
between the chloride and hypochlorite, the constitu¬ 
tion of which may be represented by the following 
formulae: — 
Ca" 
Cl 
Cl 
Chloride 
of Calcium. 
Ca"-f C1 
|(CIO)' 
Calx 
Chlorata. 
Ca" 
(CIO)' 
(CIO)' 
Hypochlorite 
of Calcium. 
[§ The solution evolves chlorine copiousty upon the 
addition of oxalic acid, and deposits at the same time 
oxalate of lime.] 
CaCICIO + H 2 C 2 0 4 = CaC 2 0 4 + H 2 0 + Cl 2 . 
[§ 1 gram mixed with 3 grams of iodide of potas¬ 
sium, and dissolved in 4 fluid ounces of water, pro¬ 
duces, when acidulated with 2 fluid drams of hydro¬ 
chloric acid, a reddish solution, which requires for 
the discharge of its colour at least 85 cubic centi¬ 
metres of the volumetric solution of hyposulphite 
of soda, corresponding to 30 per cent, of chlorine 
liberated by the hydrochloric acid.] The action of 
the hydrochloric acid on the chlorinated lime is 
this:— 
Ca Cl Cl O + 2 H Cl = Ca Cl 2 + H 2 0 + CL, 
and each atom of chlorine thus produced liberates 
an atom of iodine from the iodide of potassium. 
When that salt is present, therefore, in sufficient 
quantity, part of it is decomposed, and not chlorine, 
but iodine, is set free— 
CaCICIO -f 2 HC1 + 2 KI 
= CaCl a -F H 2 0 + 2KC1 + I 2 . 
The amount of iodine is then determined by the em¬ 
ployment of the solution of hyposulphite of soda. 
This is made by dissolving 1 molecule (248 grams) 
of the crystallized salt in water, and making the so¬ 
lution measure 10,000 cubic centimetres. This quan¬ 
tity would therefore be sufficient to decolorize 1 
atom, or 127 grams, of iodine. 
2 Na 2 S 2 0 3 5 H 2 0 -f- I 2 
Hyposulphite. Iodine. 
= 2NaI + Na 2 S 4 0 6 + 5H 2 0. 
Iodide. Tetrathionate 
of Sodium. 
If 85 cubic centimetres are necessary to decolorize 
the iodine set free by 1 gram of the calx chlorata, 
this indicates L0795 gram of iodine, and conse¬ 
quently an equivalent quantity, or '30175 of Cl,— 
10,000 : 85 : : 35*5 grams of chlorine, 
equivalent to 127 grams of iodine: '30175 gram, the 
chlorine available from 1 gram of calx chlorata. 
Since 1 gram yields '30175 of Cl, 100 grams yield 
30T75. Tins is the same as saying 30 per cent. 
