340 



Mr. J. T. Bottomley. 



[May 7, 



Professor Church, and subsequently described by Tschirch. The 

 former took chlorophyll that had become brown on standing, and 

 acting on it with zinc powder obtained a body yielding green 

 solutions, which he took to be regenerated chlorophyll. Tschirch 

 acted on Hoppe-Seyler's chlorophyllan with zinc powder and observed 

 the same phenomena, the conclusion at which he arrived being the 

 same, viz., that chlorophyll is reproduced from chlorophyllan by 

 reduction. It is probable, however, that what they obtained was in 

 reality a zinc compound of phyllocyanin, and would have been formed 

 just as well by using zinc oxide. Chlorophyllan is probably an 

 impure substance containing some fatty acid along with phyllocyanin, 

 so that by the action of zinc oxide it may yield a compound similar to 

 those above mentioned. The experiment was tried with the crude 

 product obtained by passing hydrochloric acid gas into a solution of 

 chlorophyll. Some of this was dissolved in alcohol, and the solution 

 was boiled with zinc oxide, when it gradually became of a bright 

 green like a solution of chlorophyll, but its spectrum differed, being 

 identical with that of the zinc compounds obtained directly from 

 phyllocyanin. 



IV. " On the Electric Resistance of a New Alloy named 

 Platinoid." By J. T. Bottomley, M.A., F.R.S.E. Commu- 

 nicated by Sir W. Thomson. Received May 5, 1885. 

 Read May 7, 1885. 



In the course of a series of experiments on the electric resistance 

 of various metals and alloys, and in particular on the variation of the 

 electric resistance of these metals and alloys with temperature, I 

 have examined a new alloy (called by the inventor platinoid), which 

 has turned out to have important properties. 



This alloy is the invention of Mr. F. W. Marfcino. of Sheffield ; and 

 I have to acknowledge my indebtedness to Mr. Martino for having 

 provided me with specimens of his new alloy and given me informa- 

 tion regarding it ; and for having supplied me with wires specially 

 drawn down to the finer gauges for my experiments. 



The inventor, searching experimentally for a means of rendering 

 tarnishable metals and alloys less tarnishable, had satisfied himself 

 that the addition of pure metallic tungsten imparted greater 

 density to alloys, and likewise less tendency to oxidation. Having 

 found a mode of combining a small quantity of tungsten with copper, 

 nickel, and zinc, he produced a white alloy resembling the alloys of 

 silver, which proved very little tarnishable under atmospheric 



