Action of the Atmosphere vpon neidy -deepened Soil. 443 



The following are the substances contained in an imperial 

 gallon ot" the waters of the Artesian well in Trafalgar Square, 

 London, according to the analysis of Dr. Lyon Playfair :^ — 



Grains. 



Chloride of sodium 25*724 



Snocarbonate of soda 0'709 



Bicarbonate of soda 14-5G4 



Sulphate of soda and potash 18'432 



„ magnesia 1*157 



Silicate of alumina, Mith a trace of oxide of iron . . 0'835 



Carbonate of lime 3'085 



„ magnesia 2'363 



Phosphate of magnesia 0"043 



Loss 0'27C 



67-188 



As estuary waters may percolate into the chalk below London, 

 the large amount of cldoride of sodium may be due in great 

 measure to that source. 



These analyses will serve to show tlie effect of water in 

 dissolving the mineral matters of the soil. The action of ammonia 

 in this respect has been already alluded to, but water containing 

 common salt (chloride of sodiuni) has also a great solvent power 

 upon some substances, surpassing even that of carbonic acid 

 water, Mr. Way for instance found that the double silicate of 

 alumina and ammonia was affected in the following manner : — 



Grains. 



1 imperial gallon of distilled water dissolved about 1*000 



„ of water saturated witli carbonic acid .. .. 2*527 



„ of water containing 0*1 per cent, of common salt 3*320 



„ of water containing 1*97 per cent, of common salt 23*100 



The last, it will be observed, is more than twenty times as much 

 as what was dissolved by pure water, and more than nine 

 times as much as was taken up by water saturated with car- 

 bonic acid. It has been shown liow largely salt occurs in rain- 

 water in some places ; its solvent effect may therefore be often 

 of some benefit. Mr. Way suggests that this effect of salt may 

 be the means of supplying silica to the stems of plants, and tlius 

 c.vplain tlje influence which has been observed of its application 

 strengthening the stems of the grain crops. An instance of this 

 came under my own oljservation. On the 11th June, 1853, 

 having o1)served part of a field of oats so very luxuriant that I 

 thought the crop would lodge and be rotted, I sowed upon the 

 rankest bit of it (being about 1"162 acre imp.) 2 cwt. of salt 

 durinir a very lieavy rain. Some of the adfacent portions were 

 also offering to be too luxuriant, although not so much so as the 

 piece thus treated. F^ut wlien harvest arrived, tlie salted bit, 



