RELATION OP THE BRITISH PHARMACOPOEIA TO PHARMACOLOGY. 635 
Billot’s test (Ckem. News, vol. i. p. 100) might perhaps have been included 
here. Two or three drops of an essential oil, such as bergamot, anise, or fennel, 
and a little magnesia are rubbed with the powder in a mortar, when no change 
of colour ensues if the specimen be pure Turkey or Russian root; but if it con¬ 
tains any home-grown root, the mixture assumes a tint varying from a salmon 
to the brightest rose-colour, according as there is little or much of the adultera¬ 
ting ingredient. 
Santonin. —This is Mialhe’s process (Pharm. Journ., vol. iii. p. 357) slightly 
improved. It is long and apparently complicated, but will be readily under¬ 
stood when it is remembered that santonin has the properties of a weak acid ; 
that it forms a soluble salt with lime ; that it is precipitable by acids, and in¬ 
soluble in ammonia. The tests given for the detection of other matter in santonin 
will not indicate the presence of strychnia with which santonin is said to be 
sometimes adulterated. A case is recorded(Pharm. Journ., 2nd ser., vol. iv. p. 
91) in which a fatal result followed the administration of some santonin, which 
was afterwards found to have contained twenty per cent, of strychnia. 
Sapo Mollis. —This substance is one of the articles of the Materia Medica, 
but no process is given for its preparation. This is to be regretted, for the com¬ 
mercial article is seldom fit for use in medicine, and an excellent and simple 
method of making a perfectly pure neutral oleate of potash or soft soap was at 
the disposal of the compilers of the Pharmacopoeia. In the Pharm. Journ., 2nd 
ser., vol. iv. p. 386, Wood shows that when lead plaster is rubbed in a mortar 
with carbonate of potash and alcohol, oleate of potash is formed, which alone 
dissolves in the alcohol; on distilling off the alcohol a pure soft soap remains. 
Soda: Arseni as is now officinal. It is the basis of the old “ Pearson’s 
Solution,” and was recommended to be introduced into the Pharmacopoeia 
by Bullock (Pharm. Journ., vol. x. p. 357) ; several physicians having stated 
it to be milder in its action than Liquor Arsenicalis, and moreover, the only 
form of arsenic easily admissible as an ingredient in pills. Garrod has re¬ 
cently confirmed this statement (Med. Times and Gaz., 1864, vol. i. p. 277), 
showing that patients, who from some unexplained cause, are absolutely in¬ 
tolerant of liquor arsenicalis, take Liquor Soclse Arseniatis without any un¬ 
pleasant result. Sodse Arsenias is only used, in the Pharmacopoeia, in the 
preparation of the liquor just named which is a solution of four grains of the 
anhydrous salt in every ounce of water. The arseniate of soda of the Phar¬ 
macopoeia is represented as containing fourteen equivalents of water of crys¬ 
tallization, corresponding to 404 per cent, of water, and nearly 37 per cent, 
of arsenic acid. When freshly prepared, however, the salt generally contains 
twenty-four equivalents, corresponding to 537 per cent, of water, and only 
28-6 per cent, of arsenic acid. The latter salt, however, very quickly efflo¬ 
resces in the air and is converted into the former, which does not effloresce 
even in warm air. These varying amounts of water in arseniate of soda will not 
interfere with the strength of the liquor, inasmuch as that variety of the salt 
which has no water of crystallization, that which has been dried at 300° and 
which contains nearly 62 per cent, of arsenic acid, is the one ordered to be used. 
But in prescribing sodae arsenias in pills, physicians must remember that the salt 
which will be, or ought to be, dispensed is the Pharmacopoeia salt containing 
only 37 per cent, of arsenic acid, almost twice as much of which therefore win 
have to be ordered to produce the same effect as a given weight of the soda) 
arsenias of the liquor would produce. Pharmaceutists will also take care that 
the comparatively weak salt containing twenty-four equivalents of water of 
crystallisation be not used for any preparation ; it is readily known by its pro¬ 
perty of efflorescence. 
Soda Bicarbonas. —The process and apparatus recommended for preparing 
this salt are the same as those for potassse bicarbonas, and will also be found de* 
scribed more fully in Pharm. Journ., vol. i. p. 274. 
