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. 
Vou. VIL P. U.. Pp There 
