14 



HISTORICAL SKETCH OF THE 



Fig. 5. 



After completing this apparatus, Mr. Clegg invited Dr. Henry to visit 

 Stonyhurst College, in order to examine the method he had there adopted for 

 purifying, and to test the gas. Dr. Henry had previously made some chemi- 

 cal experiments respecting the affinity of lime for sulphuretted hydrogen, but 

 gave it as his opinion that " coal-gas could not be purified from sulphuretted 

 hydrogen, on a large scale, by means of lime." I presume this opinion to 

 have been founded upon the idea of the practical difficulties attendant upon 

 the complete contact necessary to produce combination to any great extent ; 

 for his own experiments in the laboratory proved that lime would combine 

 with sulphuretted hydrogen, leaving the carburetted hydrogen free. Dr. 

 Henry refused to acknowledge the efficacy of Mr. Clegg's apparatus for puri- 

 fying, until he had repeatedly tested the gas ; after which he admitted it to be 

 perfectly satisfactory, and capable of being adopted in large manufactories. 



In 1808 Dr. Henry communicated a paper to the Royal Society, claiming 

 as his own idea the use of lime-water for the purification of gas from sul- 

 phuretted hydrogen in large quantities, without even mentioning the appa- 

 ratus of Mr. Clegg, who, having consulted Dr. Henry while proceeding with 

 his experiments at Stonyhurst, felt much pain as well as disappointment at 

 this injustice, which was the more unexpected, from the friendship that had 

 subsisted between them. After this, Messrs. Boulton and Watt erected a lime 

 machine at the Soho manufactory. 



