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V. — Contributions to the Knowledge of the Manufacture 



of Gas. 



By B. Frankland, Ph.D., F.C.S., Professor of Chemistry 

 at Owens College. 



The importance of the manufacture of gas for illuminating 

 purposes must be admitted by all, and artificial light thus 

 procured has become almost a necessary of life ; yet it is 

 remarkable how little progress has been made in this branch 

 of art, since the first few years of its existence. It is true that 

 so far as the mechanical part of the process is concerned, 

 considerable improvements have been effected, and by the 

 application of new methods of purification, we are now 

 enabled to free the gas from almost every objectionable 

 ingredient, yet, although the generation of luminiferous gas 

 depends essentially upon chemical principles, as it is the 

 modification of the force of affinity by the agency of heat 

 that determines the products of every destructive distillation, 

 it is impossible carefully to peruse the results of the late Dr. 

 Henry's beautiful and elaborate researches on this subject, 

 without being forcibly struck by the comparatively slight 

 advance which has been made in what I may be allowed to 

 call the generating department of gas-making, since that 

 distinguished philosopher applied himself to its investigation. 

 Better descriptions of coal and some new materials have been 

 tried and have come into use ; the disengagement of the gas 

 has been facilitated by decreasing the pressure within the 

 retorts ; and attempts have been made to increase the propor- 

 tion of luminiferous ingredients, by regulating the heat so as 



