TIIE VETERINARY COLLEGE PHARMACOPOEIA. 621 ) 
Of liquid tar alone I have no good opinion as a stopping; it 
is too heating and drying: mixed with the turpentine, it is worse, 
because it is more apt to dry and cake in the hoof: mixed with 
oil of tar (a strange compound, however, and not very chemical— 
a combination of the matter distilled, and that which is obtained 
from it by distillation), it is better, on account of the penetrating 
quality of the oil, or spirit of tar. For suppleing the feet, a 
compound of oil of tar and fish-oil, in the proportion of one pound 
of the tar to two pounds of fish-oil, will be useful; and, for a com¬ 
mon stopping, equal parts of tar and grease, and an eighth part 
of resin, cannot be beaten. 
Tinctures. 
Compound Tincture of Myrrh . 
Gum resin of myrrh, powdered.-- one pound 
A loes-...-.................... one pound 
Rectified spirit... ...........- one gallon. 
Macerate fourteen days, often shaking it up, then pour it off for use. 
This is generally recognised by the name of compound tincture 
of aloes, or tincture of myrrh and aloes. It is one of the best 
balsams for wounds that the practitioner has, and, indeed, super¬ 
sedes every other. 
Tincture gJ' Opium . 
Opium in powder.... two ounces and a half 
Proof spirit... two pints. 
Macerate fourteen days, and strain. 
This is the common laudanum, the use of which is sufficiently 
known. On some future opportunity, I may consider the omis¬ 
sions of this strange, incongruous document; for the present, I 
conclude with wishing that it may soon undergo that reform which 
is now so properly applied to greater things. 
A Practitioner. 
A LETTER ON A CANAL IN THE MEDULLA SPINALIS 
OF SOME QUADRUPEDS. 
IN A LETTER FROM MR. WILLIAM SEWELL TO 
EVERARD HOME, ESQ., F.R.S. 
[Copied from the Philosophical Transactions of the Royal Society, A. D. 1808. J 
Sir, 
According to your request, I send you an account of the facts 
I have ascertained, respecting a canal I discovered in the year 
1803 , in the medulla spinalis of the horse, bullock, sheep, hog, 
and dog; and should it appear to you deserving of being laid be- 
