22 
OX THE CAUSES OF CHANGE IN SEED-OILS. 
making blue-pill, which. I happen to know by experience to be a very dangerous 
one. After quoting Tyson to show that protoxide made a more certain (?) mer¬ 
curial pill than the metal, he proceeds :— u Tyson made his protoxide (black 
oxide) of mercury from calomel, also by an ingenious modification of the usual 
method. He says, ‘ But the great secret that remains, is to procure the slate- 
coloured protoxide. Aqua Calcis will not do, as it produces an ash-colour from a 
mixture of muriate of lime ; Liquor Potassse alone will not do, for it produces a 
brownish-black powder, containg a portion of submuriate of mercury undecom¬ 
posed, and which no addition of Liq. Potassae will act upon, but by the addition 
then of a small quantity of Liq. Ammoniac (as well as Liq. Potassae), the calomel 
is completely decomposed, and the slate-coloured protoxide immediately pro¬ 
duced.’ I have quoted these observations of Tyson,” confines Hr. Attfield, u be¬ 
cause I believe they contain the basis of a method of preparing a much better 
and more rational blue-pill than the officinal article ; I commend them to the 
notice of therapeutists.” 
How, Sir, it is some five-and-thirty years since, when I was an apprentice, 
that I made a substitute for Hydrargyrum cum Greta by mixing the nearly black 
precipitate obtained by the action of ammonia on calomel with chalk; and what 
was the consequence ? That I nearly poisoned some children in the n|iglibour- 
hood. It purged and vomited violently. 
The fact is, this black precipitate is not an oxide of mercury; it is (as has 
since been shown by Sir Bobert Kane) a chloro-amiduret of mercury, containing 
half the electro-negative elements that are in the officinal “ white precipitate.” I 
should not however have noticed the chemical error, only it might lead to dan¬ 
gerous practical consequences. 
I am, Sir, yours respectfully, 
John Aldridge, M.D., 
Pharmaceutical Beferee to the Pharmacopoeia Committee 
of the Medical Council. 
Lower SacJcville Street , Dublin, Lane 18, 1864. 
[P.S. Perhaps I may be permitted to indorse Mr. Abbott’s statements at the 
Leeds Association with respect to soap liniment, which I can thoroughly.] 
OH THE CAUSES OE CIIAKGE IN SEED-OILS. 
TO THE EDITOR OE THE PHARMACEUTICAL JOURNAL. 
Sir,—In your last number, Mr. Whipple objects to some statements of mine 
contained in your Journal for April last, and inserted by way of appendix to 
my paper “ On the Cohesion Figures of Liquids,” contained in your number 
for March. 
In using the terms “ gum and mucilage,” to account for the change that comes 
over certain seed-oils, I wished to explain that it is owing to the separation of 
some part of the matter of the seed with the oil, which by subsequent fermen¬ 
tation, or some similar change, induces or assists the acidification of a portion 
of the oil. The gum and the mucilage may not form the whole of the impurity, 
nor may they always be present; but one, or both, is commonly present in the 
oil obtained from the seed-presses. Woody fibre and albumen occur more or 
less constantly. But woody fibre is less likely by its change to set up a putre¬ 
factive action than gum and mucilage ; the albumen would probably be sepa¬ 
rated more readily by settlement. A scientific friend connected with the oil 
trade, to whom I am indebted for some of the information in my paper, speaks 
of the “ oil foots” as containing a considerable proportion of gum or mucilage. 
This refers more particularly to the olive-oil foots. Animal oils will, of-course, 
contain a different series of impurities. My remarks referred chiefly to cro- 
