ix 



construct the formula for that substance, which is now universally adopted. 

 This analysis was made at a time when accurate organic investigation 

 involved much greater difficulty and the exercise of higher ingenuity than, 

 with Liebig's method, is now required ; and although Erdman and Dumas 

 had from their analysis of a less pure substance deduced other formulae, 

 they afterwards confirmed that of Mr. Crum. The very ingenious method 

 proposed by Mr. Crum for the analysis of nitrates was founded on the 

 conversion of the nitric acid into nitric oxide by the action of sulphuric 

 acid on mercury. He applied this method to determine the quantity of 

 nitrogen in gun-cotton. Having determined the carbon by combustion 

 with chromate of lead, he was led to the formula of C^^ H^ 0^ + 3 NO. for 

 the most explosive gun-cotton — a result which has recently been confirmed, 

 after the most rigorous investigations, by Mr. Abel and others, and it is 

 now universally accepted. The action of sulphuric acid and mercury on 

 gun-cotton led Mr. Crura'to regard the latter as a nitrate, a view which, 

 making gun-cotton analogous to nitric ether, was long opposed by nearly 

 all chemists, but is now very generally adopted. 



Mr. Crum's investigation of the acetates of alumina is very able and 

 complete, showing the precipitating action of very dilute solutions of 

 various salts on soluble alumina, in the same manner as he had shown such 

 action at a much earlier date in the case of the sulpho-indigotates and 

 sulpho-phcenicates. His papers on the peroxide of copper and on the 

 action of nitric acid and peroxide of lead as a very delicate test for man- 

 ganese are esteemed valuable contributions to analytical chemistry. 



After the death of Dr. Thomson in 1852, Mr. Crum delivered to the 

 Philosophical Society of Glasgow a discourse on the Life and Labours of 

 his instructor, in which he dwelt with much feeling, ability, and discrimi- 

 nation on the varied acquirements and contributions to science of that 

 eminent and laborious chemist. 



Mr. Crum was remarkable for unbending rectitude of purpose and 

 love of truth, for great acuteness of perception and decision of character ; 

 and his public spirit was as notable as his perseverance in conducting to 

 a successful termination whatever he undertook. He occupied during 

 many years a high place in public estimation, and took a leading part in 

 every good work having for its object the educational, social, or poHtical 

 improvement of the people. 



In his own extensive and interesting works at Thornliebank, he had an 

 ample field for the energetic practical development of his sagacious and 

 benevolent plans for the moral and intellectual improvement of the nume- 

 rous workmen in his employment. For upwards of forty years Mr. Crum 

 devoted much time and personal effort to furthering the interests of An- 

 derson's University in Glasgow, of which he was a most liberal and effec- 

 tive patron and supporter. His election to the Presidency of that valu- 

 able institution gave him ampler opportunity for indulging his favourite 

 desire of bringing scientific knowledge within reach of the artisan and 



