122 Chemical 'Researches upon Diseased Milk, 



some mechanical or physical method : and 2dly, by the more 

 usual means ; but where, instead of seeking for the deleterious 

 substance in the atmosphere, in which it is contained only in 

 small quantity, it will be discovered in some solid or liquid 

 substance, which will furnish it in quantities sufficient for ex- 

 tensive examination. 



A. By the help of some mechanical or physical method. — 

 We can conceive the possibility of effecting the liquefaction 

 or the solidification of a miasma which was in a state of va- 

 pour in the atmosphere, either by compression or by refrigera- 

 tion. The deleterious matter thus liquefied or solidified might 

 ultimately be studied by means of oiu' present chemical pro- 

 cesses, in the same way as hydrocyanic acid, morphia, pi- 

 crotoxia, strichnia, &c. have been ; and then we should 

 no longer be compelled to admit that miasmata escape all 

 chemical analysis, or that they are imponderable fluids. Nor 

 would the result, whose possibility we now contemplate, be al- 

 together new in a scientific point of view, since Dr Fax'aday 

 has already examined the carburetic hydrogens which have been 

 separated by great compression from the common illuminating 

 gas. This instance has pre-eminently the advantage of ena- 

 bling us to perceive how the perfecting of purely mechanical 

 or physical methods, which condense or refrigerate the gas, 

 and collect the liquid or solid products of the condensation, 

 may contribute to the advancement of the sciences of che- 

 mistry, physiology, and medicine. 



B. By the assistance of the present methods. Chemistry may 

 succeed in recognising the natiu-e of a miasm, by detecting 

 it, not in the atmosphere, but by separating it from some so- 

 lid or liquid substance, or by determining its formation at the 

 expense of the proper elements of that substance ; and the 

 proof that this supposition is not unreasonable will be found 

 in the following facts. If, before the discovery of the volatile 

 acids, to which butter is indebted for its persistent and cha- 

 racteristic odour, it had been proposed to a chemist, that he 

 should discover the nature of the odorous substance which 

 pervaded several pints of air, after having been for 24 hom's 

 in contact with butter, to a certainty he would have failed in 

 all attempts, and chiefly on account of the insignificant quan- 

 tity of the odorous substance. In spite, however, of this, no 



