ANIfTTERSAET ADDRESS OF THE PRESIDENT. xH 



Mr. Thomas Cock, a brother-in-law of Mr. Johnson's, a gentleman 

 of considerable private means, and an able although comparatively 

 ■unknown amateur chemist and metallurgist*. It was in ^""illiam 

 Allen's laboratories, Plough Court, that he first succeeded in work- 

 ing the metal ; and it was at Mr. Allen's special request that he 

 showed his experiments and their results to his friend Dr. Wol- 

 laston, then visiting him. Dr. Wollaston adopted an almost identical 

 process for the manufacture of platinum ; and to him has generally 

 been accorded the credit of having discovered it. 



Mr. Thomas Cock being much interested in the work at Hatton 

 Garden, spent much of his time in the laboratories there. Mr. 

 Johnson took up the platinum-manufacture, using Mr. Cock's pro- 

 cess up to the time of his retiring from business, and always 

 remained the only platinum-refiner in England. 



His eminence as an analyst should also be noticed. So great 

 was it, that the only other commercial assayers in London, though 

 his rivals, used frequently to send him compounds or minerals of a 

 difficult and complicated nature to report upon for them. 



Probably no man has attained in his day greater perfection in 

 whatever he undertook, or was more looked up to for his opinion ; 

 and few have worked with greater perseverance, or done more for 

 the advancement of their profession. 



For several years prior to his death Mr. Johnson resided in a 

 pretty cottage, which, with an estate, picturesquely overlooking the 

 sea, he had purchased at Stoke Fleming, near Dartmouth. Al- 

 though near the scene of his fonner mi n i n g-ad ventures, and still 

 working in his well-appointed laboratory, he was repelled from 

 further participation in the mines by the conduct of some of his 

 associates. His withdrawal was felt as a serious loss both by the 

 working class whom he had befriended, and by the owners and 

 managers of mineral property, to whom he had rendered himself 

 remarkable, amid so much of dishonest and careless speculation, by 

 his intelligent and honourable conduct of affairs ; nor is it too much 

 to say that enterprise in our western mines would take a much 

 higher position if more of its leaders emulated the manly tone and 

 liberal uprightness of Percival Johnson. 



By the death of Charles Maclarex, which took place in Septem- 

 ber last, we have lost one of the veterans of geology, and a man 

 who did much, in a persevering but unobtrusive way, to render the 

 principles and aims of the science known to a large section of his 

 countrymen. 



He was born in the village of Ormiston, in the county of Had- 

 dington, on the 7th October, 1782, and at an early age, after some 

 few years of parish schooling, was intended to be apprenticed to his 

 uncle, a smith in a large way of business. But as his constitution 

 proved to be dehcate, he followed for a time the occupation of a 

 clerk and book-keeper with some Edinburgh firms, and employed 

 his spare hours in diligently acquiring a knowledge of Greek and 

 * See Aikiu's ' Dictionary of Chemistry,' 1807. 



