cclxxx GENERAL SUMMARY OF SCIENTIFIC AND 



carried on for an indefinite period, with very little loss of 

 nitric acid. 



The presence of lime in the oxide of manganese increases 

 the percentage of loss of hyponitric acid, to avoid which the 

 inventor recommends the employment of just so much lime 

 as will be necessary (the proportion by equivalents) to ox- 

 idize the chloride of manganese. By the use of this proc- 

 ess Kuhlmann claims to be able to regenerate 88 per cent, 

 of the superoxide of manganese. By the process of Weldon, 

 which is much simpler (vide Annual Record, 1873, p. cxxx 

 et seq.), some 70 per cent, is claimed. 



Hargreave's improvements in the alkali manufacture are 

 said to be makkig rapid progress, while the ammonia process 

 is not found to work so well as was at first anticipated. 

 Gruneberg & Vorster, of Cologne, have patented a process 

 of obtaining caustic soda by passing superheated steam over 

 a heated mixture of common salt and of alumina or its hy- 

 drate. 



Dr. Crookes affirms that the application of Sprengel's de- 

 vice of employing atomized liquids in operations where a 

 liquid is made to act as an absorbent of a gas has effected 

 a material improvement in the production of sulphuric acid. 

 In the ordinary process of manufacture, the sulphuric acid 

 as contained in the chambers contains about 50 per cent, of 

 water, which w 7 as once steam, and was taken as such from 

 the steam-boiler. Before condensation of this steam oc- 

 curred, this steam occupied a certain space, and moreover 

 helped (on account of its heat) to expand the bulk of other 

 gases used in the formation of sulphuric acid. In winter 

 time the yield of acid is better, and the consumption of 

 nitre less than in summer; and the greater the chamber 

 space {%. e., the smaller the volume of gas allowed to pass 

 the chambers in a given time), the less will be the compara- 

 tive consumption of nitre, and the easier will be the con- 

 version of all sulphurous into sulphuric acid. Hence, adds 

 Dr. Crookes, as the lowering of the temperature of a gas im- 

 plies the shrinkage of its volume, both of which favor the 

 process of sulphuric acid-making, Mr. Sprengel commenced 

 to manufacture sulphuric acid by means of what has been 

 called " pulverized or atomized water or spray," which he 

 injects into the chambers as a substitute for steam. This 



