322 Wisconsin , Academy of Sciences , Arts, and Letters . 
tact with a number of metals and carbonates. In some cases 
hydrogen or other gas was e-volved from the metal and a chloride 
of the metal formed. In others one metal was attacked, and 
this metal deposited from solution upon a. second metal. In 
still others, no gas appeared and no deposition of metals upon 
each other was observed but still some metals were corroded. 
Some solvents of themselves attack the metals. 
EXPERIMENTAL METHODS AND APPARATUS. 
The experimental work was conducted as follows: 
The hydrochloric acid gas was evolved by dropping an aque¬ 
ous solution into concentrated sulphuric acid; the gas then 
passed through two wash bottles containing concentrated sul¬ 
phuric acid; over fused calcium chloride contained in a tower 
30 cm. high and 3 cm. in diameter; over phosphorous pentoxide 
spread on dry pumice stone contained in (1) a tower 40 cm. 
high and 4 cm. in diameter, (2) a bottle 10 cm. high and 5 cm. 
in diameter and (3) through a tower of the same dimensions as 
ISTo. 1. From here the gas was passed into the bottle which 
contained the clean, dry metals and the anhydrous solvent. 
From this bottle the gas was led away through three tubes 2 cm. 
in diameter and 15 cm. long, containing phosphorous pentoxide, 
connected in series, then through a sulphuric acid wash bottle 
and finally absorbed in potassium hydrate solution. M> cot¬ 
ton was used in any of this work since phosphorous pentoxide 
decomposes it. Where necessary, glass wool, which had pre¬ 
viously been heated, served to keep particles of phosphorous 
pentoxide from being carried by the gas. 
Two methods of preparing the solvent were used. 1. The 
dehydrated, redistilled solvent was sealed up in a test-tube, 
placed in a clean, dry bottle which contained the clean dry 
metals and the bottle closed with a rubber stopper through 
which passed two tubes; one reached to the bottom of the bottle 
so that the hydrochloride acid gas when passed in might bub¬ 
ble through the solvent; the other tube served as an exit for the 
gas. Before any hydrochloric acid gas was run through, a 
stream of hydrogen purified by the usual means and dried over 
