•278 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



from the flowers of the Kalmia is said to produce typical symptoms. 

 The poisonous constituent is said to be identical with one discovered 

 in the related plant Pieris japonica, which Plugge named 'andromedo- 

 toxin.' A list is given of other plants in which this poison is present. 



M. L. H. 



Nitrogenous Manures, The Supply of. By E. Heine (Gartenflora, 

 April 15, 1908). — The writer points out that even the complete exhaustion 

 of the fast-disappearing beds of nitrate in Chili will not lead to a nitrogen 

 famine ; for at least three materials, which can be produced in unlimited 

 quantities, have already appeared in commerce. 



In the first place, a method has been perfected by which the 2 per cent, 

 or 3 per cent, of nitrogen contained in peat is obtained as a by-product, 

 in the form of ammonia, in the process of extracting from the peat a 

 gas, which can readily be utilised as a source of power for industrial 

 purposes. The practically inexhaustible supplies of peat in various 

 regions of the world may therefore be made to produce vast quantities 

 of nitrogenous manure in the form of sulphate of ammonia. 



Another source of nitrogen for horticultural purposes is calcium 

 cyanamide. This substance readily parts with its nitrogen under the 

 influence of the bacteria in the soil, and is produced by heating calcium 

 carbide in the air., The nitrogen is thus obtained direct from the 

 atmosphere, where the supply is inexhaustible. The necessary carbide 

 can be produced economically wherever electric power is cheap, for it is 

 obtained by fusing calcium and carbon in the electric furnace. 



Lastly, Norway has taken- the lead in obtaining nitrogen from the 

 atmosphere by employing a very powerful electric arc to combine the 

 elements of the atmosphere into an oxide of nitrogen. From this nitric 

 acid is obtained, and the substance eventually put on the market is 

 calcium nitrate. For this is claimed the advantage over Chili saltpetre, 

 that, whereas the sodium of the latter is useless in the soil, the lime of 

 the calcium nitrate is usually a very valuable addition. — W. B. D. 



Oil of Tar as an Insecticide. By E. Wallis (Jour. Dep. Agr. 

 V%ct. t February 1908, p. 100). — The following is the formula used 

 successfully in spraying for pumpkin-beetle : Crude oil of tar, \ pint ; 

 soft soap, \ lb. ; caustic soda, 1 oz. ; water, 5 gallons. Boil one pint 

 water and in it dissolve soap and soda ; add oil of tar, and agitate well. 

 Then add the mixture to remainder of water (hot), agitate, and use. 

 Confine attention chiefly to leaves on which beetles have swarmed and 

 use a good garden syringe to spray mixture on plant. 



The wholesale price of crude oil of tar is about 5s. per gallon. The 

 pumpkin-beetle also attacks cherry trees ; the habits of the beetle make 

 it easy to destroy by contact, as they congregate in large numbers on a 

 leaf, whilsl the other leaves of the plant may remain untouched, 

 and only a few of the beetles attempt to take flight when the plant is 

 Bprayed. Crude oil of tar was found more effective in destroying this 

 ins. el ih.in i ither Paris vreen. arsenate of lead, or " Carbysol." — G. II. II. 



Olearia ramulosa var. communis. By J. Hutchinson (Bot. Mag. 

 tab. 8205). — Nat. ord. Co?nj)ositae, tribe Asteroidcae Australia. Shrub 



