and the Black Oxide of Iron at a white heat. 181 



electric sparks and discharges in a syphon eudiometer over 

 water, with the same negative results ; but when air or oxy- 

 gen was mingled with the gas, it exploded sharply with 

 heated platinum or the electric spark. When a match was ap- 

 plied to the open end of a tube containing the unmingled gas, 

 it burned rapidly with a pale blue flame, but did not explode. 

 The gas given off during the action of the fused globules on 

 water was not then a mixture of oxygen and hydrogen. 



Its freedom from all but a trace of oxygen Avas ascertained 

 in other ways. To. one portion of the gas standing over water 

 nitric oxide was added, but no ruddy fume or yellow colora- 

 tion showed itself. When phosphorus was introduced into 

 the gas, in one instance it did not smoke, but in the greater 

 number of cases it fumed for a brief period, and occasioned 

 an amount of contraction barely perceptible. The gas ap- 

 peared to be nearly pure hydrogen. To ascertain if it cer- 

 tainly were so, a portion of it was carefully dried, by chloride 

 of calcium, and transferred to a eudiometer over warm mer- 

 cury. Dry oxygen was then added, and the mixtiu'e exploded. 

 When the whole had cooled, the walls of the eudiometer ap- 

 peared dimmed by a very thin layer of moisture, but the 

 quantity of gas operated on was too small to admit of visible 

 drops being produced. Another portion of the gas was mixed 

 with half its volume of oxygen and fired by the electric spark. 

 The contraction which followed explosion varied in different ex- 

 periments, but was frequently such as to leave not more than 

 one-twentieth part of the mixed gases unconsumed. Phos- 

 phorus smoked in this residue for a short time, showing that 

 excess of oxygen had been made use of, and left a minute 

 volume of gas which was not diminished by caustic potash, 

 and must have been nitrogen. 



It seemed possible that the trace of carbon present even 

 in malleable iron might affect the quality of the gas resulting 

 from the action of the globules of oxide on water, and that 

 carburetted hydrogen, carbonic oxide or carbonic acid might 

 be produced. It seemed desirable to know whether the latter 

 were present or not, as the oxygen might have gone to form 

 them. It was impossible to be certain that carbonic acid 

 was absent, for the gas from the globules being necessarily 

 collected over water, the temperature of which was low, car- 

 bonic acid would be retained in solution by that liquid. All 

 that I can say on this point is, that lime-Avater was not ren- 

 dered muddy or in the slightest degree opalescent by the 

 gas. It was several times detonated with oxygen over lime- 

 water, but the latter remained quite transparent, so that nei- 

 ther carbonic oxide nor carburetted hydrogen can have been 

 present. In short, the gas evolved from water by the white- 



