1870.] Air-Pollution by Chemical Works. 331 



however, although he is rid of it, his neighbours are not so ; they 

 find, on the one hand, that the water of their brook is no longer fit 

 for use, nor pleasant to look at, and the air they breathe is polluted 

 with unsavoury and noxious vapours. Where a manufactory of this 

 kind stands alone, or where only those who are dependent on it for 

 their subsistence dwell in its vicinity, this state of things goes on for 

 a long time without calling forth much complaint. Sooner or later, 

 however, complaints must come ; we cannot all live at arm's length. 

 Population increases, we are pressed together, and valuable though 

 the various products of manufacturing industry may be, pure air 

 and pure water are more valuable still. Yet We cannot do without 

 the manufactory, unless we return to barbarism. A naked savage 

 eating uncooked roots erects no chimney to pour its black or acrid 

 vapour into the air; he discharges the liquor from no dye back into 

 the clear brook of the glen — but he remains a savage. We must 

 keep our manufactories ; by their products we are warmly clothed, our 

 houses are firmly built and are decorated with colours ; the wind is 

 shut out by panes of transparent glass ; the paper on which we write 

 is white and fair. These and a thousand other things are the results 

 of many a mechanical or intricate chemical process, the waste 

 products from which, solid, liquid, and gaseous, are unpleasant 

 enough. 



If, then, we will not go back to barbarism to get rid of our 

 smoke and our dirty water, can we go forward and by greater skill 

 dimmish or suppress them ? The answer must be " Yes." Yet those 

 only who have to work out the problem know with what difficulty 

 this answer has in many cases been given, whilst in many it is not 

 given yet. 



The materials which the manufacturer throws away, we have 

 already classed in correct school-room fashion as solid, liquid, and 

 gaseous. With the first of these the manufacturer alone is con- 

 cerned, and it may be safely left in his charge. The more of it he 

 produces, the more must he expend in its removal, the more land 

 must he purchase on which to deposit it ; and if he throws away 

 that which is valuable, he is the chief loser. We may, therefore, 

 safely leave him, with certain reservations, to look after his solid 

 refuse, knowing that no sharper impulse can be applied to induce 

 him to diminish its amount, or to save what is valuable in it, than 

 the spur of self-interest which already exists. We say it may be 

 safely left in his charge ; but if, through some process of fermenta- 

 tion or change, a portion of it shall slip out of his custody, and 

 yield, after rain, a noxious liquid to drain into the nearest brook, 

 or a gaseous escape to contaminate the air around, it falls back into 

 the two other classes. 



For the present we propose to direct attention to the latter of 

 these two classes only, the gaseous. In doing so, we would first dwell 



VOL. VII. 2 A 



