142 



negative electrode couipk^te reduction occurred in about one-tliird the time. 



In order furtlier to compare the activity of nasc-ent hydrogen made in 

 contact with different metals pieces of slieet copi^er, tin and phitinum as 

 nearly equal in exposed area as possible were each made the negative elec- 

 trode from a battery giving practically tlie same current. The cell con- 

 tained the same quantity, in solution, of acidified dichromate. The hydro- 

 gen in all cases reduced the solution in about the same time. 



Finally a glass tube al)Out five feet long and one centimeter bore, sealed 

 at one end, was filled with a good grade of granulated zinc whose surface 

 had been cleaneil l»y wasbiiig. in turn, with arid, water, amnidnium hydrox- 

 ide and large quantities of distilled water. A solution of chromic acid 

 was made by dissolving a small quantity of chromium trioxide in water 

 which had been jiurified by iv-distilling ()nliiiary distilled water from alk.-i- 

 line permanganate ;ind using only tiie middle fraction which was again 

 l)roug]it to boiling for a few minutes inunedialely before using. The tube 

 containing the zinc was tilled with this solution and then one-half of it 

 replaced by well purified hydrogen free from air. The open end of the 

 tube was connected to a smaller tube le.-iding to a vessel of mercury to 

 prevent the escaiK? (>f hydrogen and to indicate any change in the volume 

 of the latter. The tube was then placed on a talde in a horizontal position 

 so that one-half of the zinc was in the liipiid and one-half in contact with 

 tile hydrogen. The tube remained in this jiosition from January niidh to 

 October .seventeenth last, i:\cept for two months during the summer the 

 tube was observed daily. No ch.inge in |)ressure o<-curred except that due 

 to dianges of temperature, and no amount of hydrogen was evolved. The 

 solution perhajis, liecame slightly ligliter in color. On oiiening the tube the 

 hvdrogen buiMied quietly. A little sulphuric acid added caused the solution 

 to become as dark as at the liegiiining. A little sediment was found in the 

 tube which looked like zinc oxide. Acid :ind zinc added to the solution 

 cati.sod rapid reduction. 



In connectitm with the s.-une subject some ])reliminary work has lieen 

 done on the reduction of jtotassium perm.-mg.inate. I'nrilied hydrogen 

 passed into a dilute aque<ais solution of the i>ermanganate decolored the 

 solution in less than twelve hours f(U-ming a brown deiM>sit. In the pres- 

 ence of iilatinum foil the redu( tion was more rapid, sometimes being com 

 plete in one liour. If the platinum were allowed to remain in contact with 

 the solution for some time the reduction with hydrogen seemed to be even 



