116 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



at which he pays for a ton of the same. The Fertilisers and Feeding 

 Stuffs Act does not take into account purchases of less than half a 

 hundredweight, and horticultural fertilisers practically do not come 

 within its scope. There is no reason, however, why, where manure is 

 used in quantity, purchasers should not avail themselves of the provisions 

 of the Act and obtain the definite guarantee of the fertilising ingredients 

 and the quantity of each present which the Act compels to be given ; 

 this should also be invariably done in purchasing chemical manures such 

 as superphosphate, bones, basic slag, kainit and other potash salts, 

 Peruvian guano, nitrate of soda, and the like. In all such cases the help 

 of the chemist can usefully be employed, and even as regards the many 

 '•'specialities" sold, and which people will always insist on having, it 

 would be well to ascertain, by chemical examination, whether these are 

 (1) suitable for the purpose ; (2) whether, all things considered, their cost 

 bears some reasonable relation to their intrinsic worth. 



Other Departments of Chemical Work. 



There remain to be briefly noticed some other spheres in which 

 chemistry may usefully come in to aid the horticulturist. In the treat- 

 ment of insect and fungoid attacks on plants a great variety of substances 

 are used, all of which require to be watched in order to see that they 

 really are what they are represented as being, and that they are likely to 

 be efficacious. Moreover, it is often the case that these are inferior or 

 even adulterated. Under this head come such material as flowers of 

 sulphur, soft soap, preparations of tobacco, sulphate of copper, and 

 preparations of it with lime for spraying potatoes and tomatoes, soot, rape 

 dust, lime in its different forms, chloride of lime, carbolic acid and other 

 disinfectants. Sulphate of copper has frequently been found to be adul- 

 terated with the much cheaper sulphate of iron ; soot, again, is a most 

 variable material, and if purchased can seldom be depended upon. 

 Another class of articles are the many sold under the name u weed- 

 killer," and in most of these arsenic compounds figure. 



In the building and renewal of greenhouse and other structures paints 

 form a not inconsiderable item, and it is well to make sure that the 

 quality of these is what it should be. I have had to examine many 

 samples of white lead, and in not a few instances I have found these to be 

 largely made up with adulterating materials such as sulphate of baryta, 

 sulphate of lime, cVc. 



Conclusion. 



While I have endeavoured in the foregoing to put out some points in 

 which a knowledge of chemistry may be made useful to the horticulturist 

 for the better understanding of the processes which go on in plant life 

 and growth, and for the application in practice of the principles which have 

 been laid down, it is only right that I should in conclusion indicate some 

 of the limitations which have to be put : in short, to name some of the 

 things which chemistry cannot do. First among these I would admit 

 that chemistry has as yet failed to give any explanation as to why one 

 plant likes this or that particular ingredient, or rejects one or the other. 



