408 



SCIENCE, 



[N. S. Vol. XXV. No. 637 



different cathodes and also with the addi- 

 tion of various substances to the solutions; 

 It was found that magnesium used as 

 cathode gave a high current efficiency. 

 Comparative results gave the current effi- 

 ciency in a solution of potassium chloride 

 to which sodium ehromate had been added 

 as 69.3 per cent., and in a potassium chlo- 

 ride solution with a magnesium cathode 

 as 65 per cent. On a continuous run the 

 efficiency of this cathode in making chlorate 

 was 90 per cent, the first hour and 60 per 

 cent, from the fourth through the eighth 

 hour. In making hypoclilorite with a 12.5 

 per cent, salt solution the efficiency was 

 96 per cent, for the first hour and 75 per 

 cent, for the ninth hour. The loss of 

 magnesium was very small. It was found 

 that from one third to one half the salt 

 could be converted and a current yield of 

 from 60 per cent, to 70 per cent, could be 

 obtained. In addition to this advantage, 

 the power cost is low. The hypochlorite 

 solution is quite clear and ready for use 

 after dilution. 



A Plea for the Systematic Study of Amer- 

 ican Gas Coals: H. B. Harrop. 

 Standard fields like the 'Pittsburg' are 

 now working down to poor grades, while 

 many areas now believed to be unsuitable 

 may yet be proved satisfactory. Knowl- 

 edge of location, extent and character of 

 various coal deposits capable of supplying 

 gas works and by-product oven plants is 

 very meager both among gas engineers and 

 commercial chemical engineers. Qualities 

 of coal required for gas works and ovens 

 discussed: gas yield, character of gas, im- 

 purities, quality of coke, tendency of ash 

 to 'clinker,' and suitable carbonizing treat- 

 ment. The author discusses, in the light 

 of his own experiments, the merits and 

 failings of the crucible volatile matter test 

 and the practicability of a standard ap- 

 paratus for determining the best carbon- 



izing temperature, gas yield and character 

 of gas. A committee is recommended to 

 cooperate with the Coal Mapping Subcom- 

 mittee of the American Gas Institute. 



Viscosity and Lubrication : Chas. F. Ma- 



BEBY and J. H. Mathews. 



This paper presented results on the 

 chemical composition, viscosity and dura- 

 bility tests of lubricating oils, manufac- 

 tured from different petroleums, and the 

 composition and viscosity of the principal 

 constituents of commercial lubricating oils. 

 The hydrocarbons examined and separated 

 from the crude petroleum from different 

 fields, as well as from the lubricating oils 

 themselves, were of the series of hydro- 

 carbons, CHon+si CnHjn, C„H2n-2, CnHjn.^. 



The viscosity of these series varies regu- 

 larly from the series dHon+o, which is very 

 low, to the series C„H2n,_4, which has a very 

 high viscosity corresponding to the high 

 viscosity of lubricating oils made from the 

 heavy petroleum that is composed largely 

 of the series, CHj,,, C„H2n_2, CnHjn-v 

 The durability tests corresponded to the 

 variation in viscosity. Viscosity was de- 

 termined in the apparatus of Ostwald, and 

 calculated from his formula 

 )i = «„(M/Wo)- 



Viscosity of these products was also deter- 

 mined by the Saybolt universal viscosi- 

 meter. The durability tests were made on 

 a bearing under 500 revolutions carrying 

 a load of 500 pounds, with a regular addi- 

 tion of the oil at the rate of six drops per 

 minute, during the first two hours. Dur- 

 ing the tests readings of temperature were 

 taken at intervals of five minutes and the 

 friction was also determined from readings 

 of weights on a balance taken at the same 

 intervals. The coefficient of friction was 

 calculated from the formula F = WL/B 

 where W^dif. in wt. lbs.; L = length 

 of lever ; E = radius of axle. A compari- 

 son of various lubricating oils showed that 



