FORMULAE IN THE BRITISH PHARMACOPOEIA. 
51 
Dr. Anderson, in his present letter to us, says—“ I think further evidence is 
required to show that thebolactic acid is really isomeric, and not identical, with 
lactic acid. So far as I recollect, Stenhouse merely determined the consti¬ 
tution of the acid, and did not make such a comparison of its salts with those 
of the ordinary lactic as seems necessary to establish this point in a thoroughly 
satisfactory manner. We now know two kinds of that acid, the common 
variety, and sarcolactic acid, and if you clearly showed that thebolactic acid 
is a third, it would be a matter of the greatest interest, and would well repay 
the labour it requires.” 
While Mr. Watts, in his Dictionary, says—“ Anderson was not able to detect 
the existence of thebolactic acid in opium,” Anderson says—“ In my investi¬ 
gations of opium I have not attempted to prepare thebolactic acid, but have 
confined my attention entirely to the basic constituents of opium.” 
We could not object to any one doubting that thebolactic acid was not the 
result of change in the juice of the poppy after exudation or during manipu¬ 
lation, in the manufacture of morphia and other principles, any more than we 
could object to such a view in regard to meconic acid ; but we think that until 
the natural existence originally of these acids is disproved, it is fair to hold them 
as “ well determined ” constituents. We would feel obliged to any one throw¬ 
ing more light on the matter, even if they proved the non-existence, naturally 
or originally, of thebolactic acid in opium. 
MEMORANDA ON SOME FORMULA IN THE BRITISH 
PHARMACOPOEIA. 
BY DANIEL HANBUItY. 
In the formula for preparing Mistura Ferri composite q a few small alterations 
suggested by experience appear worthy of notice, and although attention has 
already been drawn to one of them, the moment seems opportune for again re¬ 
ferring to the subject. 
The first point I would notice is the Myrrh , which (as often stated) should 
not be in powder , as the long desiccation required for reducing it to that state 
deprives it of much of its aroma. A piece of fine lump myrrh answers better * 
there is, moreover, an advantage in allowing the myrrh to soften by contact 
with the water during some hours, before the emulsion is completed. This 
emulsion is usually kept ready prepared, the sulphate of iron being added when 
the mixture is required to be sent out. As no chemist would probably prepare 
for stock less than a pint of it, I would adapt the formula to that quantity. 
According to the British Pharmacopoeia, each fluid ounce of the emulsion re¬ 
quires 3f grains of sulphate of iron: it would be rather more convenient to 
reduce this proportion to 3J grains to the ounce, the mixture of the London 
Pharmacopoeia being grains. 
With these changes, the following would be the formula for 
MISTURA FERRI COMPOSITA. 
II Ferri sulphat. grs. 70. 
Potas. carb. grs. 60. 
Myrrh do, 
Sacch. aa drms. 
Sp. myrist. fl. drms. 2^. 
Aq. rosoe, q. s. 
Triturate the myrrh and carbonate of potash with the sugar and sufficient 
rose water to form a thin paste. Set this aside for twelve hours; then 
