Medical Chemistry. 81 
P.S. Lregret very much, to find the Geological Ob- 
servers in your vast and interesting country, so very com- 
monly to omit stating bearings and distances, from known 
Towns, aswell as nearest distances and bearings from known 
Streams, as the means of more pefectly fixing the localities 
of their particular observations, and conveying an idea of 
the same to Readers here and elsewhere, who-can have no 
other helps than Maps, and those perhaps, not on the larg- 
est scale, or latest construction. [tis an equal source of 
disappomtment and regret, that the direction and degree of 
Dip, is not invariably mentioned, wherever Rocks or Strata 
are observed. Incomparably the most simple and useful 
mode of denoting the latter, is, by the proportion of the 
measure of level, to one of perpendicular fall: as for in- 
stance, Dip NE 1 in5, or SW 1 in 2, &c.; and #5 ory,* 
may on Maps, denote the same things, as I have long prac- 
ticed. I hope Mr. Editor, that you will join me herein, 
and not fail to reiterate the request, that Observers of Stra- 
ta, of useful Minerals, in particular, like Coal, Limestone, 
Freestone, Ironstone, Gypsum, Clays &c. will always in- 
elude the above particulars, in their descriptions sent for 
your work. 
MEDICAL CHEMISTRY. a 
=} ee 
PRUSSIC ACID. 
Art. VII. Abstract and translation of Dr. F. Macenpre’s 
late publication on Prussic Acid—by the Eniror, with re- 
marks. 
"THE memoir of Dr. Magendie of Paris, presented to the 
academy of sciences of that city, Nov. 17, 1817, on the 
uses of the Prussic acid in certain diseases, particularly in 
Phthisis Pulmonalis, was published, soon after, in English, 
in the Journal of the Royal Institution of Tecnico aa is 
generally known in this country. 'The subject is one which 
* Mr. Farey’s marks in his MS. are arrow heads ; no characters of nearer 
resemblance were at hand. 
Von. If.....No.-1. 11 
