1817.) Scientific Intelligence. 331 
not too much concentrated. Into a diluted solution of sugar of 
lead (completely dissolved by means of nitric acid) drop tartaric 
acid as long as any precipitate falls. Then filter the solution, and 
set it aside. In 24 hours the tartrate of lime (if any be present) 
will be deposited in minute crystals.—Nitrate of lime enables us to 
separate oxalic acid from tartaric. Dissolve the mixed acid in 
water, and pour nitrate of lime into the dilute solution. The 
oxalate of lime falls; but the tartrate remains in solution.—T,. 
VIII. Query respecting Stains of the weaker Acids, 
(To Dr. Thomson.) 
SIR, Bedford-square, March 10, 1817. 
I shall feel myself much obliged by you, or any of your corres- 
pondents, favouring me, through the medium of the Annals, with 
a ready method of destroying the stains made by the less caustic 
acids, as those of citric, oxalic, &c. It has been sometimes asserted 
that an alkali will destroy them; but I have ineffectually tried that 
method; and, I imagine, should any method be discovered, it 
would be found extremely useful. 
With regard to your information respecting diabetic urine, I feel 
myself extremely obliged to you as far as it concerns the Annales de 
Chimie ; but not having devoted much time to the study of foreign 
Janguages, your information would be more acceptable in the Eng- 
lish, Latin, or French, rather than in the Swedish, German, or 
other languages. 
Iam, Sir, with the most profound respect, 
Your obliged humble servant, 
IX. Query respecting Artificial Camphor. 
(To Dr, Thomson.) 
DEAR SIR, 
If you will have the kindness, by means of your Annals, to state 
the process of preparing artificial camphor, you will much oblige, 
Yours truly, 
March 16, 1817. J. Morson. 
<3. 
For a description and history of the mode of making artificial 
camphor, I refer my correspondent to my System of Chemistry, 
fourth edition, vol. v. p. 74.—T. ' 
X. Chemical Composition of Minerals. 
I have considered the ingenious letters of An Electro-Chemical 
Theorist with some attention, and agree with him that his mode of 
calculation is necessary for bringing the analysis of minerals under 
the pale of the atomic theory. The theory of Berzelius is different, 
and indeed is nothing else than the reduction of all analyses under 
his grand chemical canon, that the oxygen in acids is always a 
