THE ALUMNI JGURNAL. 



309 



a modification of a process proposed by 

 Mr. William Gossage, in 1837, for re- 

 covering the manganese that had been 

 used in the manufacture of chlorine. Mr. 

 Gossage had proposed to treat the resid- 

 ual liquors of this manufacture by lime, 

 and to oxidize the resulting protoxide of 

 manganese by bringing it into frequent 

 and intimate contact with atmospheric 

 air. This process — and several modifi- 

 cations thereof subsequently patented — 

 had been tried in various places without 

 success. Mr. Weldon, however, did 

 succeed in obtaining a very satisfactory 

 result, possibly — even probably — because 

 not being a chemist, he did not add the 

 equivalent quantity of lime to his liquor 

 to precipitate the manganese, but used 

 an excess. However, Mr. Weldon, if he 

 was not a chemist at that time, was a 

 man of genius and of great perseverance. 

 He soon made himself a chemist, and 

 having once got a satisfactory result, he 

 studied every small detail of the reaction 

 with the utmost tenacity until he had 

 thoroughly established how this satis- 

 factory result could be obtained on the 

 largest scale with the greatest regularity 

 and certainty. 



He even went further, and added con- 

 siderably to our theoretical knowledge 

 of the character of manganese peroxide 

 and similar peroxides by putting forward 

 the view that these compounds possess 

 the character of weak acids. He ex- 

 plained in this way the necessity for the 

 presence of an excess of lime or other 

 base if the oxidation of the precipitated 

 protoxide of manganese by means of at- 

 mospheric air was to proceed at a tufii- 

 ciently rapid rate. He pointed out that 

 the product had to be considered as a 

 manganite of calcium, a view which has 

 since been thoroughly proved by the in- 

 vestigation of Goergen and others; and it 

 is only fair to state that Weldon' s process 

 is not only a process for recovering the 



peroxide of manganese originally used, 

 but that he introduced a new substance, 

 viz. : manganite of calcium, to be con- 

 tinuously used over and over again in 

 the manufacture of chlorine. 



Mr. Weldon had the good fortune that 

 his ideas were taken up with fervency by 

 Colonel Gamble, of St, Helens, and that 

 Colonel Gamble's manager, Mr. F. 

 Bramwell, placed all his experience as a 

 consummate technical chemist and en- 

 gineer at Mr. Weldon's disposal, and as- 

 sisted him in carrying his ideas into 

 practice. The result was that a process 

 which many able men had tried in vain 

 to realize for thirty years became in the 

 hands of Mr. Weldon and his coadjutors 

 within a few years one of the greatest 

 successes achieved in manufacturing 

 chemistry. 



The Weldon process commences by 

 treating the residual liquor with ground 

 chalk or limestone, thus neutralizing the 

 free acid and precipitating any sulphuric 

 acid and oxide of iron present. The 

 clarified liquor is run into a tall cylin- 

 drical vessel, and milk of lime is added 

 in sufficient quantity to precipitate all 

 the manganese in the form of protoxide. 

 An additional quantity of milk of lime, 

 from one-fifth to one-third of the quan- 

 tity previously used, is then introduced, 

 and air passed through the vessel by 

 means of an air compressor. After a few 

 hours all the manganese is converted in- 

 to peroxide; the contents of the vessel 

 are then run off, the mud, now every- 

 where known as "Weldon mud," is sett- 

 led, and the clear liquor run to waste. 

 The mud is then pumped into large 

 closed stone stills, where it meets with 

 muriatic acid, chlorine is given off, and 

 the residual liquor treated as before. 



HOW weldon's process works. 

 You note that this process works with- 

 out any manipulation, merely by the 

 circulation of liquids and thick magmas 



