340 



PROCKEOINCK OK THE 



nnnod with a view to astcrlaiii whetlier any of it had been ab- 

 sorlk-d by t!ie plants that had been thus treated, and similar ones 

 >»hit h had not been so watered were gathered, and care taken to 

 select ^<iod clean plants, so as to derive no impurity from the 

 soil. On examination it was found that those watert^ with the 

 muriate of lime did not, any more than those ^rown under ordi- 

 nary conditions, c<»ntain nrnj nuiriate of lime. A preat difference 

 was found in the relative per cent.u^e of muriatic acid ; for those 

 watered with muriate of lime contained 8 '.> nuiriatic acid, whil?t 

 the others contained only 7 ■ i lie muriatic acid in both cases 

 was combined with alkali, and not with lime ; it is tolerably cer- 

 tain that the muriate of lime had been decomposed by alkaline 

 Sidts present in the sod. 



As I have already stated, the action of saline compounds is 

 very little understood, and I will not therefore go much further 

 into the subject, as the only conclusions I could at present come 

 to would of necessity be theoretical. I will however draw at- 

 tention to one more point. An opinion is held by many that the 

 idkalies must be in combination with a weak acid, because plants 

 are unable to separate them from compounds with strong acids. 

 Dr. Daubeny when speaking of the sulphate of ammonia, says : 

 ** there is no reason to beheve that the organs of a vegetable cm 

 decompose sulphate of ammonia, and if they were able to do so, 

 the disengagement of free sulphuric acid in consequence, could 

 hardly fail to be injurious to their structure." If we assume that 

 salts of ammonia are merely valuable to plants as sources of 

 nitrogen, the above view would be a necessary conclusion ; but 

 there appears good reason to believe that these salts have other 

 action besides merely supplying ammonia, and that their absorp- 

 tion by plants can produce other effects than the one just men- 

 tioned. Precisely the same eCTects can be produced by* sulphate 

 of soda, as by nitrate of soda, on some plants ; and the explana- 

 tion which might be given in the latter case that the nitrate sup- 

 plied nitric acid, and consequently nitrogen in a form capable of 

 being assimilated, could not be adopted in the case where the sul- 

 phate was used. Some common Pelargoniums were watered with 

 a dilute solution of sulphate of soda, and after a short time the 

 effects produced became visible in the rich green colour of the 

 leaves, and shortening of the distance between the nodes, precisely 

 the same as if nitrate of soda had been employed. On exami- 

 nation it was found that the principal difference between ihem and 

 common Pelargoniums was, that they contained more Sulphate 

 of soda. The green plant fed with sulphate of soda contained 

 14 parts of sulphuric acid in 10,000 of the plant, whilst the 

 other contained but 8 in a similar weight ; in the latter case 



