232 



oxygen of tlie air with the hot vapour of the metal^ it being a 

 well-known fact that mercury in contact with oxygen at a high 

 temperature becomes oxidized. In silver smelting greatly im- 

 proved results are nov/ obtained as compared witli those of a few 

 years ago, doubtless owing to the employment of skilled metallur- 

 gists, but that there is a considerable loss of lead is evidenced by 

 the fact (if evidence were wanting) that a large number of persons 

 at Broken Hill show some of the minor symptoms of lead-poison- 

 ing. In Europe great efforts are made to condense lead fumes as 

 completely as jDossible, so as to recover the metal. Probably 

 enough it would not pay to erect condensing flues for this pur- 

 pose at such places as Broken Hill, but the fact remains that 

 there is waste, and such waste as might make a considerable 

 difference in large works employed in smelting poorer ores, and 

 may we not hope to see metallurgical processes so carried out in 

 Australia in the future as to render possible the profitable treat- 

 ment of such poorer ores. 



CHEAP SALT. 



Closely connected with the possibility of preparing chlorine by 

 a paying process is the production of cheap salt. Surely there 

 should be little difficulty about that. For this purpose the salt 

 need not be purified at all, but the residue from sea water or salt 

 lakes used just as it is, and in the hot dry parts of this colony 

 near the seacoast large quantities of sea water could be evaporated 

 at a very small outlay. Moreover, I cannot see why good salt 

 for table and other domestic purposes should not be manufactured 

 in quantity as it is on the shores of the Mediterranean by the aid 

 of the sun's heat alone. If there is a prejudice against colonial 

 articles there must be some cause for it. Probably the sending 

 into the market of carelessly manufactured and imperfectly puri- 

 fied products has had a good deal to do with it ; and in this par- 

 ticular instance the evaporation of sea water needs to be carefully 

 carried out to produce a good marketable article, while that salt 

 obtained from salt lakes, the result of inland drainage, is sure to 

 contain considerable quantities of magnesium compounds, which 

 will render it bitter and unsuitable for domestic use, unless means 

 are taken to remove these objectionable substances. If our 

 colonial manufacturers are to succeed it is absolutely necessary 

 that good articles should be produced. 



ECONOMY IN THF USE OF GAS. 



In recent years a great deal has been done in the direction of 

 economizing fuel in large works requiring the use of powerful 

 furnaces. It is well known that the gases which escape from 

 ordinary closed furnaces are not completely burnt. The com- 

 plete combustion of these gases is now effected by introducing 

 under certain conditions a secondary supply of air, this air being 



