TILE FLOKAL WORLD AND GARDEN GUIDE. 309 



Monsieur G. Henderson. — Greyish rose, with purple centre. 



Mons. Linden. — Bright crimson, with strong glow of salmon ; 

 remarkably bright and telling. 



Mons. Marin Saison. — Fine rosy crimson, with fine rich eye. 



Professor Koch. — Bright red, shaded with vermilion. 



The Deacon. — Rich rosy purple, with fine crimson eye. 



Virgo Marie. — Pure white, with purple centre, immense flowers 

 and truss. 



DAGGER OF GAS-LIME IN GARDENS AND 

 PLANTATIONS. 



BY DR. T. L. PHIPSOX, F.C.S., 



Member of the Chemical Society of Paris, etc. 



IT. ia not unusual for gardeners to place a layer of gas- 

 lime as a bed for the gravel of garden walks and 

 terraces. I have seen it used recently on rather a 

 large scale in this manner. It appears that it checks 

 or prevents, for a very long time, the growth of grass 

 and weeds on the newly-gravelled walks, so that they look new and 

 clean for a considerable period, extending over one, two, or more 

 "seasons." I have also seen gas-lime spread over the surface of 

 old gravel walks in order to hill patches of grass and weeds, etc. 



These operations, especially the former, are very dangerous to 

 the larger trees and shrubs in the neighbourhood. Gas-lime is lime 

 which has been used to purify street gas, and it has absorbed a 

 certain number of highly poisonous ingredients. The chief of these 

 are sulphocyanide of calcium, sulphocyanide of ammonium, sulphide 

 of calcium, a green and a blue compound of iron and lime contain- 

 ing sulphur and nitrogen, besides certain hydrocarbons similar to 

 benzole, naphthaline, creosote, and carbolic acid, etc., which are 

 highly injurious to vegetation. 



Recently I have seen two fine cedar trees, and some smaller 

 fir trees of various kinds, attacked by the noxious influence of gas- 

 lime, spread under the gravel walks of a large garden about five 

 months ago. One of the cedars began to recover after an interval of 

 four months ; but the other still appears with blackened leaves, and 

 to all appearance quite dead. It is doubtful whether it will recover. 

 The large roots of these trees spread under the gravel walks in all 

 directions, and the poisonous compounds contained in the gas-lime, 

 some of which are very soluble, are carried down to them by the 

 rain. As soon as they come in contact with the roots, the effects 

 produced are almost as sudden as those of lightning. Cedars, and 

 certain kinds of Abies, appear to be particularly sensitive in this 

 respect. 



On gravel walks, treated as above, large blood-red patches appear 

 in the course of a month or two ; they are caused by sulphocyanide 

 of iron, which results from the union of the sulphocyanic acid of the 

 gas-lime with the iron oxide contained in the gravel. Sometimes 



