212 



ON THE AIR AND RAIN OF MANCHESTER. 



compelled therefore merely to examine the rain. All the 

 rain was found to contain sulphuric acid in proportion as it 

 approached the town, and with the increase of acid the 

 increase also of organic matter. 



The existence of albuminous compounds may be traced in 

 the rain, however carefully collected, and the still further 

 vestiges of living creatures, minute animalcules, may be found 

 also. These creatures are sufficient of themselves to shew 

 the existence of phosphates, whilst sulphates and lime may 

 be readily obtained. In examining the Thames water I 

 often found that the readiest way of collecting the phosphates 

 and magnesia was to wait for the animalcules to do it. When 

 the residue of the rain is burnt, an abundant evolution of 

 ammonia may be obtained ; but I have not ascertained the 

 amount, because it varies much, and I do not well feel able to 

 collect all the ammoniacal salts which may have existed in 

 the rain, as so much loss is caused by evaporation, even if 

 an acid is present. All results hitherto obtained must have 

 been approximative and too low. 



This organic matter, however, is capable of decomposing 

 and of forming ammonia when it falls upon the ground, and 

 of furnishing food to all kinds of plants. There is enough 

 therefore to grow plants scantily, although experience shews 

 that there is not enough to produce a crop of any value. I 

 do not regard it however as the object of nature to manure 

 the land by rain — one more important and practical is to 

 purify the air ; and there is enough of evidence to shew us 

 that places entirely without organic matter may become 

 covered with it, and also to shew us that plants nourished 

 even by rain water only may be made to grow. 



This shews also the possibility of large quantities of impure 

 matter being kept afloat in the air, indeed it is scarcely pos- 

 sible to obtain the vapour of water without some such impure 

 matter. The organic matter found in the rain seems to be in 

 perfect solution, and no doubt the more decomposed portion 



