644 
NOTES AND ABSTRACTS IN CHEMISTRY AND PHARMACY. 
BY C. H. WOOD, F.C.S, 
The Action of Light on Citrate of Iron and Quinine. 
I was engaged about two years ago in preparing some citrate of iron and qui¬ 
nine, and by scaling my product in a hot cupboard, I obtained good-sized scales, 
•—bright, of a golden-green colour, and perfectly soluble in water. Remembering, 
however, that potassio-tartrate of iron gives far better scales when scaled in 
the sun’s rays, than by any artificial heat (a fact I learnt from Mr. Braithwaite), 
I spread some of my solution on plates of glass, and exposed them in a win¬ 
dow to an April sun. I was soon surprised, however, to observe the citrate be¬ 
coming darker in colour and exhibiting a very good photographic image of some 
bottles which cast their shadows on the plates. After a time, but while still 
wet, it gradually became opaque, as if the quinine had been precipitated. It 
ultimately came off in minute brownish-coloured powdery scales. The two 
results from the same solution were as different as they possibly could be. The 
sun-scaled specimen when put into water became white and opaque, and only 
dissolved after the lapse of a long time. The scales produced by heat, when 
thrown on water, rapidly melted, retaining their perfect transparency to the last. 
The salt contained 17 per cent, of quina. 
I then thought it would be worth while to ascertain whether the strong solu¬ 
tion only is subject to this change, or whether the finished product would be 
also affected in like manner by exposure to light. About a drachm of the good 
citrate, scaled by heat and dissolving freely without opacity, was therefore spread 
out on a sheet of white paper and laid in the sun’s rays. After a quarter of an 
hour’s exposure, it was perceptibly deepened in colour. In twenty minutes it had 
become brownish, and when put into water became at once white and opaque. 
The white spongy bits floated about in the liquid, and gradually, but slowly 
dissolved. Some samples of citrate of iron and quinine were then obtained 
from several different makers, and exposed in the same manner. All were 
more or less similarly affected, but nevertheless the results varied considerably. 
In some cases the salt was even more decidedly affected than my own had been ; 
but in others the result was less injurious, and when the scales, after insolation, 
were treated with water, although they became white and opaque, their ulti¬ 
mate solution took place rapidly. Portions of these exposed specimens were 
wrapped up and put away in a dark place for some time ; upon subsequently ex¬ 
amining them, they had to a great extent passed back to their original con¬ 
dition. It has often happened that samples of this salt have been disparaged on 
account of their difficult solubility; from these results, however, it would ap¬ 
pear possible that this defect has not been so much due to any fault in the manu¬ 
facture as to some accidental circumstance in the preservation of the product. 
Should time and opportunity offer, I hope on some future occasion to investi¬ 
gate more fully the nature of the change which thus occurs in citrate of iron 
and quinine by exposure to light. 
The Solubility and Estimation of Quinine. 
M. Fausto Sestini* has made some new determinations of the solubility of 
quina in pure water. He finds that one part of quina requires 1667 parts of 
water at 20 ° C., and 902 parts at 100° C. for its solution. One part of the 
hydrate of quina (with 3 H 2 0) requires 1428 parts at 20°, and 773 4 at 100° C. 
The alkalies diminish the solubility of quina, and soda to a greater extent 
than potash ; a ley containing one-sixth of soda dissolving none. The author 
has analysed several arseniates of quina, in which he estimated the alka- 
* ‘ Bulletin de la Societe Chimique/ Fevrier 1869. 
