CHEMICAL DETERMINATIONS CONCERNING THE SOIL. 133 



intensity of the need of potash and phosphorus. A caution is 

 required here ; all plants do not need the same relative propor- 

 tions in their foods. Tornatos, for example, require potash and 

 chlorine, and there are few soils which would not be improved 

 for Tomato-culture by kainit, which contains large amounts of 

 both these constituents ; but the continuous use of kainit on a 

 Vine-border would be very undesirable, although some, in the 

 absence or defiance of chemistry, are recommending it. The 

 chlorine the Vine does not need, and suffers from its presence if 

 pronounced ; here nitrate of potash would be infinitely better, 

 as proved both by theory and experience. 



Our tests may be simplified by using leguminous plants, 

 as nitrogen, which other orders require with hardly an excep- 

 tion, is not helpful to them, as previously explained. If 

 French Beans be taken as a test crop, we proceed as before, but 

 three pots will be sufficient, and lime may be included in the 

 inquiry, since leguminous plants commonly require this in large 

 amounts. The pots will then be manured with potash, phos- 

 phorus, and lime, and the behaviour of the plants will determine 

 the peculiarity of the soil under inquiry. 



HARDY RHODODENDRONS AND AZALEAS. 

 By Sir John T. D. Llewelyn, Bart., F.R.H.S. 

 [Read June 6, 1893.] 



Most people are struck with admiration at the brilliant and 

 glowing colours of the genus Rhododendron, and those who care 

 to give more than a passing glance at their beauties, who will 

 also take interest in their specific distinctions, or judge the hardy 

 hybrids by the tests of colour, shape of the truss, shape of the 

 pip, and by the spotting of each pip, will doubtless be further 

 interested to prolong the blooming season during which they 

 may enjoy their treasures. 



The two common species, common in gardens and shrubberies 

 in the last century, and still abundant where tins lovely genus 

 thrives, are Rhododendron ponticum and Rhododendron cataw- 

 biense. 



