ON MURIATIC ACID GAS, &C. 297 



run into a small portion in the bottom ; the sides were bedew- 

 ed for a length of six inches, and a thin film of moisture ap- 

 peared beyond, nearly its whole length. 



By the muriatic acid gas being extricated in the preceding 

 experiment from nearly dry materials, and by its previous 

 transmission over an extensive surface of loose muriate of lime, 

 it was inferred, that it would be free from hygrometric vapour ; 

 and that it held no moisture, was apparent from no trace of it 

 appearing in the anterior portion of the tube. To obviate, 

 however, entirely, any supposed fallacy from this source, the 

 experiment was performed in the following manner. One 

 hundred grains of clean and perfectly dry iron filings were put 

 into a long glass tube, which was placed, as before, across a 

 small furnace. Muriatic acid gas had been kept in contact 

 with dry muriate of lime for three days, in a jar with a stop- 

 cock adapted to it. This was connected, by a short tube with 

 a caoutchouc collar, with the tube containing the iron filings ; 

 and a little of the muriatic acid gas being passed through the 

 tube to expel the air, the temperature was raised to ignition. 

 The slow transmission of the gas was continued by the pres- 

 sure of the mercury in the quicksilver trough, and fresh quan- 

 tities, which had been equally with the other exposed to mu- 

 riate of lime, were added, as was necessary. Water almost im- 

 mediately appeared in the tube beyond the iron filings, it col- 

 lected in spherules, and continued to accumulate as the gas 

 continued to be transmitted for a length of about seven inches. 

 A portion of the gas which escaped from the extremity, was 

 clouded, and deposited a film of moisture on the sides of the 

 jar in which it was received over quicksilver. The quanti- 

 ty of gas transmitted amounted to about thirty-five cubic 

 inches. 



Vol. VIII. P. II. P p There 



