266 Formula for calculuting the Force of Steam. 
of the essential oils ; and if chewed, it sticks to the teeth like resin. 
Whether this is the new resin, and the other the gum resin, which 
M. Stromeyer has mentioned, it is impossible for me to say, or 
whether his experiments were made with the coal-tar which con- 
tains them. Whether essential oil may be obtained in sufficient 
quantity to render it worth extracting, am not prepared to say. 
But that the ammoniaeal liquor will yield sal ammoniac so as to 
pay for the labour and expense, I have no doubt:—but more of 
this on some future occasion. Suffice it for the present to say, 
that if any of the foregoing hints shall in the least help, or stir 
up others who may have more ability and opportunity for deeper 
research than myself, I shall rest satisfied that I have neither 
wasted my own time, nor your pages. 
With great respect I remain yours, &c. 
Derby, March 15, 1819. Gro. Lowk. 
_ P.S. Having read the discovery of a new combination of oxy- 
gen, hydrogen and carbon, called lampic acid, have any of your 
correspondents observed the peculiar ethereal smell arising from 
the slow combustion of coal gas when issuing from an Argand, the 
cock of which is turned on so little as only to give a blue flame 
about a quarter of an inch high; will the cause of one account 
for the other ? 
* * We beg to add, for the information of our correspondent, 
that. the principal consumption of the ammoniacal liquor at pre- 
sent is by the sal ammoniac makers, Mr. Lowe put on the mar- 
gin of the communication he sent to us, several pencil dashes of 
the two colours described in the foregoing paper: they appear to 
be pretty solid, and may possibly possess other properties which 
may add to their value. The suggestion in his P.S. is ingenious, 
aud we doubt not will soon be put to the test of experience. 
XLIII. Formula for calculating the Force of Steam. By 
Mr. W. Creicuton. 
To Mr. Tilloch. 
Sir, — Tx your Number for February, Dr. Ure having given 
some formulas for calculating the elasticity of aqueous vapour, I 
am induced to communicate one formed some years ago to suit 
Mr. Dalton’s experiments, especially as it is simple, and the re- 
sults frequently nearer Dr. Ure’s numbers than his own ealcu- 
lations. 
Let the degrees of Fahrenheit +85=D, and the correspond- 
ing force of steam in inches of mercury —G-09=I. Then 
Log. D—2:22679 x 6= Log. I. 
Example. 
