1809.] 
Among the numerous methods recom- 
mended for preserving Pencil and Chalk 
Drawings, I have never yet found any 
so really efficient, as that 1am about to 
communicate ta-you. 
Most persons run their drawings over 
with a large camel-hair pencil dipped in . 
milk, (which is an undoubted preserva- 
tive from rubbing,) but they are generally 
spoiled in the operation, as very few can 
avoid smearing the loose- particles of 
lead which remain on the surface of the 
paper at the ume they are running the 
milk over it: besides this, the milk leaves 
a disagreeable glutinous appearance upon 
the paper, which, in a great measure, 
destroys the effect of the drawing. 
‘To remedy these evils, I adopted ano- 
ther process, winch not only preserves 
the drawing from being rubbed, quite as 
well as the former, but has the additional 
advantage of keeping it perfectly clean 
at the same time. The process is as fol- 
lows: 
ist. Get a pan, or tub, sufficiently spa- 
cious to admit the drawing horizontally ; 
fill it with clean water, and run the 
drawing through in that direction; then 
lay it on something flat to dry.* ‘This 
will take off the loose lead already men- 
tioned. 
Qdly. Fill the same vessel a second 
time, with rather more than one-third 
new inilk,+ and the remaining part clean 
water, through which run the drawing 
again horizontally, and leave it to dry as 
before. 
This, Sir, is the whole secret and pro- 
cess, by which I have preserved some 
hundreds of pencil and chalk drawings ; 
and that it may prove equally serviceable 
to those of your late friend, is the ardent 
wish of, Sir, Your's, &e, 
Farnham, Surry, Sept. 12. Go; 
To the Editor of the Monthly Magazine. 
SIR, 
T is asserted in Bewick’s History of 
Quadrupeds (p. 16), that mules have 
sometimes been known to bring forth 
* Do not lay the drawing, while wet, on 
any coloured wood, such as mahogany, &c, 
which will stain the paper in streaks, 
+ Should milk be scarce, you may mix a 
litle (in the proportions above-mentioned, ) 
in a tea-cup, and venture to run the drawing 
lightly over with a camel-hair pencil, the 
water having already taken off the superfluous 
lead, and, in some degree, fixed the other ; 
but be particularly light with the pencil, 
never touching the drawing twice in the 
same place. 
Method of preparing Aromatic Vinegar. 
461 
young, and that instances are not want- 
ing of their having bred in England and 
Scotland. This is a very curious and im- 
portant fact in Natural History, of which 
I never knew one instance: indeed, I 
have often heard it very much doubted 
by men very eminently distinguished for 
their knowledge of that science. If, 
therefore, any instances of this kind have 
fallen under the notice of any of your nue 
merous and widely-dispersed correspond 
ents, by communicating them to the pub-= 
lic, through the channel of your interest= 
ing Mavazine, they will much oblige, Sir, 
London, Your's, &c. 
Sept. 29, 1809. S. BR, 
Ea 
To the Editor of the Monthly Magazine, 
SIR, ; 
HERE are many insulated facts in 
chemistry, with which individuals 
are well acquainted ; but owing to care- 
lessness or indifference, the public remaia 
for years withoat a knowledge of thea, 
Of such is the following: 
Take of common vinegar any quantity; 
mix a sufficient quantity of powdered 
chalk, or common whiting, with it, to 
destroy the acidity. Then let the white 
matter subside, and pour off the insipid, 
supernatant liquor; afterwards let the 
white powder be dried, either in the open 
air, or by a fire. When itis dry, pour 
upon it sulphuric acid (oil of vitriod, as 
long as white acid fumes continue to 
ascend. Stone vessels are the properest 
to be used on this occasion, as the acid 
wil not act upon them. This product 
is the Acetic Acid, known in the shops 
by the name of Aromatic Vinegar. The 
simplicity and cheapness of this process 
points it out as a very useful and come 
modious one for purifying prisons, bos- 
pital-ships, and houses, where contagion 
is presumed or suspected, the white 
acid fumes diffusing themselves quickly 
around, 
If any one were desirous of obtaining 
the acid in a liquid state, the apparatus 
of Nooth presents a convenience for the 
purpose, It must of course be collected 
in water. . 
Your's, &c. 
James JENNINGS. 
Huntspill, Sept. 23, 1809. 
P.S. In my letter of September, on Sperma 
Ceti, page 167, please to make the follow- 
ing correction—Instead of ‘¢ You are to put 
them in a dottle, containing one-third water,” 
read, ‘* You are to put them in a furnace, 
&c.”” 
Te 
