TRANSACTIOXS OF SECTION B. 



■07 



changes to about 20, and ultimately to about 24. But tbis increment is 

 really arrived at by 8 steps, giving in the tirst instance an average of 2'0 for each 

 element ; iu point of fact, however, the increments are not regular, being for the 

 first line, and starting with lithium, 2-1, 1-9, 1-0, 2-0, 2'0, 30, and then 4-0 for two 

 steps, the intermediate one being unknown. This departure from regularity in the 

 increment seems to show that it is of a compound nature ; that the original 

 substance may run through the whole series, but be modified by small quantities 

 of one or more additional substances. This would seem to explain not only the 

 slight irregularities, but how our place in Mendeljetf's arrangement may be occupied 

 by two or more elements which closely resemble one another, but differ very 

 slightly in atomic weight or in other properties, such as the iron group, the plati- 

 num group, the two didymiums, and the metals associated with yttrium. On this 

 supposition the elements having high atomic weights may be expected to be loss 

 regular than is the case in the earlier part of the series. 



6. The Heating and Lighting Potcer of Coal Gas. 

 By T. Fairley, F.R.S.E., F.LC. 



The author pointed out the importance of knowing the heating power of gas 

 as well as the lighting power, now that it is so largely used for heating and 

 engine purposes. 



Coal gas is a complex mixture consisting chiefly of marsh gas and hydrogen 

 with small quantities of heavy hydrocarbous, oxides of carbon, aqueous vapour, 

 nitrogen, itc. The first two control mainly the heating value, and the heavy 

 hydrocarbons the lighting value in ordinary burners. Incandescent gas-burners 

 are not considered in this paper. 



That heavy hydrocarbon vapours raise the lighting more than the beating 

 power, explains why carburetted water-gas has a less heating value than ordinary 

 coal-gas of the same lighting power. Air or nitrogen drawn into gas lowers the 

 lighting power more than the heating power. 



In gas made from one kind of coal the calorimeter may be worked constantly 

 so as to watch the gas in place of the jet photometer. 



The author referred to the various calorimeters invented, and gave directions 

 for securing accuracy. Finally he gave a table of average results showing the 

 heating power of gas of different lighting power. 



Heating power. Pounrls 

 of water heated 1° F. 

 by 1 cubic foot of gas. 



533 



555 



578 



tOl 



Lighting power, 

 Standard candles. 



11 

 12 

 13 

 14 



7. On Smoke. By J. B. CoiiEX, Ph.D. 



Department II. 



1. Bradford Sewage and its Treatment. 

 By F. W. Richardson, F.I.C, the Bradford City Analyst. 



In times of normal trade over twenty tons of wool-grease come every weekday 

 into the city's sewers. AVool-suds and effluents, in addition to grease, contain 

 enormous amounts of nitrogenous impurities ; thus it is that Bradford sewage is 

 one of the very worst sewages iu the kingdom. Of the daily dry-weather flow of 

 twelve million gallons of sewage one and a quarter millions consist of -woolcomters 



z z 2 



