1816;} > On the Ventilation of Coal-Mines. 288 
together, we obtain no direct combination between them; but 
phosphureted hydrogen gas is disengaged, and phosphate of potash 
remains behind in the liquid. Hence the affinity of the alcohol is 
indispensable to produce phosphuret of potash, a ) 
The aphrodisiac property well known to belong to phosphorus in- 
duced me to try if the phosphuret of potash possessed the same 
effects on animals; and my first attempts promised complete 
success. If I succeed in establishing this effect, this property of 
phosphorus may be taken advantage of, without being exposed to 
the inconveniences so frequently resulting from the direct use of 
this substance. I propose to publish in a particular memoir the 
manner of administering this remedy ; the precautions requisite to 
prevent the decomposition of the phosphuret of potash in the 
stomach, and to add the cases in which it has been employed with 
moore or less success, 
ArtTicLe VII. 
On the Veniilation of Coal Mines. By Lieut, James Menzies, of 
the 68th (or Durham) Regiment of Foot. With a Plate. 
(To Dr. Thomson.) 
DEAR SIR, , Newcastle-on-Tyne, Nov. 13, 1815, 
In my last letter I hinted to you that I had for some time back 
been endeavouring to arrange what I conceived might be an im- 
provement in the ventilation of coal-mines; and that I had been 
interrupted by the arrival of a Gentleman, who, it was said, had a 
new system of ventilation to offer, which possessed the decided ad- 
vantage of having been already tried in the Staffordshire mines with 
effect. 
ye 1 a now learned that his plans of ventilation have been re- 
jected; that two other plans were deliberated upon at the same 
time, one of which had the preference ; but whether with the in- 
tention of adopting it, 1 have not ascertained. I may venture, 
however, to predict that no mew plan of ventilation will take place 
in this quarter for some time to come. 
It too frequently happens, when a person has made, or fancies he 
has made, a discovery of so much importance as a perfect system of 
ventilation must unquestionably be, that he also fancies it to be so 
extremely simple as to require some degree of secrecy, lest others 
should take advantage of it to his detriment ; and at the same time 
so extremely perfect that little more is requisite than to stipulate 
upon what terms it may be employed. 
However well founded these ideas may be in particular cases, so 
far as relates to the ventilation of coal-mines in the north of Eng- 
land they are yompletely erroneous, There are strong deeply 
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