Examination of the Minerals , <$c. 
375 
1830.] 
diminished by a constant number. The ratio of this progression is the same for 
all bodies, and is equal to 1,0077. 
3rd Law. The rate of cooling in vacuo, for the same excess of temperature, 
increases according to a geometric progression, the temperature of the surrounding 
matter increasing in arithmetical progression. The ratio of this progression is 
also 1,00' 7 for all bodies. . , 
4 th Law. The rate of cooling, as alTected by the contact ot a gas, is entirely 
independent of the surface of the body. 
5 th Law. The rate of cooling, as due to the contact of a gas, varies in geome- 
tric progression, the excesses of temperature forming also a geometric progression. 
If the ratio of this second progression be 2, that of the first will be 2,35, what- 
ever the nature of the gas, or whatever be its tension. 
This law may also be stated, by saying, that the heat abstracted by the contact ot 
a gas is, in alfcases, proportional to the excess of temperature ot the body raised to 
tb 6/A°LaL! ,2 The cooling power of an elastic fluid diminishes in geometric pro- 
gression, when its tension diminishes in a geometric progression. If the rat'oot 
this second progression is 2, the ratio of the first is 1,36b for an , , > 
drogen; 1,431 for carbonic acid ; and l ,4 1 5 for olefiant gas. Or we may s^e this 
law as follows : The cooling power of a gas is (all things else teing equal I as a 
certain power of the tension. The exponent of tins power, which depends on the 
nature of the gas, is for air ,45 ; for hydrogen ,315 ; for carbonic acid ,517 , 
“; 1 l 0r z.°'^ a Tlfe ' '«£Sin. power of a gas varies with its temperature hat in 
such manner, that if th/gas can dilate itself, so as to continue J'iu'bi, 2' much 
pressure, or preserve the same elastic tension, the cooling power will beas much 
diminished by its rarefaction as it is increased by its rise of temperature, so that 
*TlXtl°n e ^ «Ie"s— ^rU’orS^propositions, that the total 
law of coolino- which must be made up of a combination of all these particular 
laws must be’ very complicated ; we shall not, therefore, attempt to express it m 
1 ’ . r „ \y e have given it under a mathematical form in the corn se 
Of tl!^ Lmofr, Which will allow** discussion, as to all the consequences to which 
one by one, the several causes which combine to give the total eff . 
II .-Examination of the Minerals collected by E. Stiring , te 
Turquoise Mines , near Nishapur m Persia. By J. 1 rmsep, B j. 
F. It. S. Sec. Phys. Cl. rlv. Sue. 
[Read a. a Meeting of the Physical Class of the Asiatic Society, 27th Oct- >a:^J 
An interesting account of these ^ 
ravels in Korasan, page 408 20. A of repea ting a few of the authors 
jr immediate reference, I shall ta description of the minerals brought thence 
jeal observations, before proceeding to a dtscnption oi 
^•hW which the mines are 
nr, and is c “""^ r "'* n ieTtbe “alter are of a primitive character, but the h.ll 
ranch from the JMberz range . and formation. 
f ,VI.,dan totally .^ers rom them .n appea,, net and ^ ^ 
_ upder decomposition, 
nbling red chalk. + . __j with iron : in some places the metal 
The whole, range is evidently ^j^vei^an^masses. . , . 
iy be seen in the form ot specular > natives, is found only in the pnn- 
fhc turquoise, or ftrdzah, as it is called y hitherto been discovered, or, 
.alhiU of the cluster j that is to say, no mine lias 
