7 8 THE POPULAR SCIENCE MONTHLY. 



we advanced a single step toward the comprehension of First Cause ? 

 We say, no ! but on the contrary are receding from it ; for we assume 

 that the vast continuity of effects which we call the universe, past and 

 present, must have had an antecedent cause, and this First Cause, which 

 certainly must be more potent than the universe it created, we assume 

 existed and preexisted without cause. That is to say, we rise from the 

 smallest phenomenon in Nature b} T slow gradations, connecting cause 

 with effect, until we reach the highest phenomenon above Nature, and 

 this we assume came into existence without cause, or in other words 

 the source of all other powers is itself an underived power, and either 

 created itself or was never created, either of which is unthinkable. It 

 is, indeed, the conception of a vast and stately intellectual pyramid 

 resting upon a vast base, which it is assumed requires no support. 



Let no devout critic challenge the physicist to explain primary 

 causation until he can show the capacity of the finite mind for the 

 reception of such an idea, nor on the other hand deceive himself with 

 the idea that he has removed the difficulty by simply covering it with 

 a name, the meaning of which is utterly incomprehensible. 



LIQUEFACTION OF THE GASES. 1 



By GASTON TISSANDIER. 



II. 



AT the very moment when Cailletet was subjecting successively to 

 the test of his apparatus the six permanent gases, and was con- 

 quering their resistance to compression, M. Raoul Pictet was making 

 his experiments, first on oxygen, then on hydrogen. But what gives 

 a special interest to the labors of Pictet is the fact that he has succeeded 

 in producing a quite appreciable volume of these gases in the liquid or 

 in the solid state. He describes his apparatus as follows : 



A and H (Fig. 1) are two compound exhausting and forcing pumps, 

 so coupled as to produce the widest possible difference between the 

 pressures of exhaustion and compression. These pumps act on anhy- 

 drous sulphurous acid contained in the tubular receiver C. The press- 

 ure in this receiver is such that the sulphurous acid evaporates at the 

 temperature of 65 C. a The sulphurous acid pumped out is carried into 

 a condenser D, cooled by a current of cold water ; it is there liquefied 

 at a temperature of 25, and at a pressure of about 2| atmospheres. 

 The sulphurous acid returns to the receiver C by a small tube d as 

 fast as it is liquefied. 



JE and F are two pumps precisely the same as the preceding, and 



1 Translated, with some abridgment, from La Nature, by J. Fitzgerald, A. M. 



2 The degrees of temperature here noted are all according to the centigrade scale. 



