liv Annual Report of the Council. 



assistant. Here they worked on the absorption of hydrochloric 

 acid and ammonia in water and later on the effect of heat on 

 solutions of the volatile acids. They ascertained that strong 

 and weak solutions of such acids when boiled, each leave a 

 residue of definite composition depending on the pressure at 

 which the boiling took place. 



In 1857 Roscoe was elected as Frankland's successor in the 

 chair of chemistry in Owens College, Manchester, at the early age 

 of twenty-four. Here he was soon occupied in a research on 

 perchloric acid and its hydrates and salts, and with Thorpe's 

 assistance he was able to show that thallium perchlorate was 

 isomorphous with the perchlorates of potassium and ammonium. 



But the chief research with which Roscoe's name will always 

 be associated was his investigation of the rare metal vanadium 

 and its compounds. In 1865 copper was being obtained at 

 Alderley Edge and the waste products were found to yield a 

 blue solution which did not give the reactions for copper salts. 

 This was brought to Roscoe's notice and it was soon recognised 

 that it contained vanadium. Such an opportunity for studying 

 the metal was not to be lost, and very soon the whole of the 

 waste product was transferred to the cellars of the old Owens 

 College in Quay Street. Many difficulties were encountered in 

 obtaining pure vanadium compounds from this source, but they 

 were eventually overcome and the purified products were used 

 for an elaborate research. The chief results obtained need only 

 he briefly referred to. It was shown that the atomic weight of 

 vanadium estimated by Berzelius as 68*5 was incorrect and 

 the true value 51 '3. The Swedish chemist had prepared the 

 oxychloride, but considered it the trichloride, and based his 

 calculations on that erroneous assumption. Roscoe showed 

 that the volatile liquid was really an oxychloride like phosphorus 

 oxychloride and that the element belonged to the phosphorus- 

 arsenic group. The metal itself had not been previously ob- 

 tained but was prepared by the reduction of the dichloride in a 

 current of hydrogen. 



