466 
ON THE MANUFACTURE OF CITRIC ACID, 
• 
and who see no obstacle in the way of progress and improvement. These are 
the men who will push forward and save the trade. These are the men who 
will free us (if, indeed, it is possible to do so) from the inexorable routine to 
which v r e are firmly chained, and thus engender in our minds that regard for 
our daily duties without which we cannot possess an adequate zeal for the pro¬ 
secution of the higher branches of our profession. 
Chemists’ Associations are a step in the right direction. Union, organization, 
strength, knowledge, power—all these mean success, and something more. 
When, therefore, the failure of an attempt to organize and unite, is reported 
in the Journal, it cannot but be a matter of regret to all w^ell-wishers of the 
trade; but though a discouragement for a time, it will detract nothing, as we 
may hope, from that one desideratum which is all but within our grasp, and in 
the possession of which (so uncertain and unsatisfactory is our position now) 
we shall be only too ready to feel and admit that “not another comfort like to 
this succeeds in unknown fate.’’ 
Let the Birmingham gentlemen try again, for although, as I have said, 
Chemists’ Associations do not flourish , in the strict sense of the term, yet wdiilst 
they exist they offer an opportunity for friendly intercourse with our neighbours 
and colleagues, and add something to the progress of pharmaceutical science as 
revealed to us in conformity vuth the times in which we live. Apologizing for 
trespassing so largely on your space, 
I am, Sir, yours obediently, 
A Major Associate. 
February 16, 1866. 
P.S. I ought, perhaps, to say that personally I have no cause for complaint 
as regards the above, since the establishment in which I am engaged is closed 
at nine o’clock every evening, and we manage to make up a good and satisfac¬ 
tory return, vdtkout having recourse to that remorseless and cruel, but never¬ 
theless intensely significant characteristic of our business, Sunday trading. 
ON THE MANUFACTURE OF CITRIC ACID. 
BY FREDERICK ROW, F.C.S. 
As so little attention has hitherto been given to the manufacture of this and other 
organic acids by scientific men (probably on account of the small quantity annually 
produced), a few observations from practical experience may not be uninteresting. 
The first point of importance in this manufacture is the defecation of the lime or 
lemon-juice imported, and from which almost all the citric acid of commerce is pro¬ 
duced. 
This juice contains, beside the citric acid, a large quantity of colouring-matter, muci¬ 
lage, and other impurities, which in the ordinary method of working so contaminates 
the citrate of lime next produced as to render the subsequent solution, and also the 
crystals of citric acid, so impure, that repeated re-crystallization and re-saturation are 
necessary to render them fit for the market. 
Hitherto it seems to have baffled the efforts of manufacturers to overcome this diffi¬ 
culty, and hence the great cost at which the acid is prepared; but the writer of this 
paper lias found that when the concentrated juice is diluted to the same strength as the 
fresh juice (which contains about twelve ounces of citric acid to the gallon) that a great 
part of the mucilaginous and other impurities will separate by subsidence in a fiocculent 
form, and the citrate of lime and also the citric acid produced from the juice so purified 
will be in a state of comparative purity. 
Another very important point for consideration of the manufacturer is the way in 
which the solutions of these acids are evaporated ; the sulphuric acid necessary to be in 
slight excess at first so accumulates in percentage by the repeated evaporation and 
