ON THE CHOICE OF FORMULA. 
119 
American Pharmacopoeia, (Boston 1820,) that of Antwerp, 
(1812,) the Batavian Pharmacopoeia, (1805,) that of Belgium, 
(1825,) those of Edinburgh, Hanover, &c. &c. Now in all 
these works, the division of the medicinal weights, is the 
same as in England, that is to say, the pound is divided into 
twelve ounces, the ounce into eight drachms, the drachm into 
three scruples, and the scruple into twenty grains, five of 
which are equivalent to six of the French. Further, without 
exception, all give under the name of compound spirit of 
lavender the London formula. Hence it results, most evi- 
dently, that every where Fowler's solution contains one 
hundred and twentieth of its weight of the oxide of arsenic, 
that it is of a beautiful red colour, and possesses the odour 
of lavender. 
If we consult the formularies and treatises published in 
France, it will be found that the formula of London has been 
more or less literally translated, without having regard to the 
difference of weights, and that arsenic does not constitute but 
the hundred and forty-fourth part of the liquid, which is 
sometimes red, as that of Cadet and Ratier, at others colourless 
as that of MM. Henry and Guibourt who direct the tincture 
of lavender, although M. Guibourt has pointed out the dif- 
ference in weight in the second edition of his Pharmacopoeia, 
without having conformed to it. If we turn to the Codex of 
1818, we will find, under the name of Liquor of Fowler, a 
solution containing the hundredth part of its weight of oxide 
of arsenic in place of the hundred and twentieth, colourless 
instead of being red, and exhaling the odour of melissa instead 
of that of lavender. 
The authors of the Codex have, in truth, determined with 
great precision, how many drops of their solution are required 
to represent a grain of arsenic, but this does not prevent the 
occurrence of errors. Should a French physician desire to 
repeat experiments made elsewhere, with Fowler's solution, 
his first care will be to examine, how many drops of the 
solution he must administer to his patient in order to obtain 
the results indicated. Now it is evident, that if he does not 
