ACETYLENE. 



309 



dition ammonia 0-24-0-4 per cent, sulphuretted hydrogen 0-7-0-9 per 

 cent, phosphuretted hydrogen 0-018-0-032 per cent (Chuard).i 



Properties. — Acetylene is a colourless gas with a slight alliaceous 

 odour ; it burns with a bright flame. One kilogram of calcium carbide 

 disengages 300 litres of acetylene. 



Action on Plants. — Acetylene has no injurious action on plants. 

 Leoni found that the germinative capacity of peas and grain did not 

 suffer from its contact. At a certain strength it must, however, act 

 like coal gas, which is known to be injurious to plants. 



Action on Fungi. — Calcium carbide applied with the bellows, like 

 sulphur, and projected on to the fungi moistened with water, appears 

 to be injurious to them, but it only kills the fungi touched. Moreover, 

 the action of acetylene on fungi is still badly understood. 



Action on Insects. — Placed in an atmosphere containing 10 per 

 cent of acetylene insects die in twenty-four hours. Perfect insects and 

 larvae of the pea weevil. Bruclms {Bruchus jnsi, L.), hidden in the peas 

 die by the acetylene disengaged when they are enclosed with a small 

 piece of calcium carbide in a closed space. 



Use. — Oidium Tuckeri, Berk, (oidium of the vine). — Huchet was the 

 first to try calcium carbide on the vine to kill oidium. After moisten- 

 ing the diseased grapes with the spraying machine, finely pulverized 

 calcium carbide was applied by a sulphur bellows. The effect pro- 

 duced was decisive, and in spite of the great heat, neither the grapes 

 nor the leaves suffered. Since then calcium carbide was tried, com- 

 paratively, against sulphur in Champagne in the vineyards of Chandon 

 de Briailles, with the result that sulphur and calcium carbide cannot 

 be used indifferently in the different phases of the disease. When a 

 stock attacked by oidium has been treated with sulphur, it may be 

 taken for granted, if rain does not intervene and if the weather is warm, 

 that the viae has been protected against the disease for a month at 

 least. But the very great efficiency of sulphur when the disease is 

 recent is less when the attack is an old one. Calcium carbide does not 

 kill tho oidium except when it is in contact with the fungus, and, more- 

 over, so that it can act the attacked grapes are moistened when the 

 carbide dust is projected on to them. Under such conditions, the 

 action of the product is somewhat energetic on strongly attacked grapes. 

 In similar circumstances the action of sulphur would be less pro- 

 nounced. The use of calcium carbide would not appear to be in- 

 dicated except on grapes to overcome an old and intense attack of 

 oidium, when the sulphurings have not been numerous enough or 

 when weather conditions have diminished the destructive capacity of 

 sulphur. 



Gitignardia Bidwelli, V. and E. (black rot of grapes). — In the 

 beginning of September, G. Eodies dusted with calcium carbide the 

 tendrils of the still green grapes attacked with black rot. Some days 

 after this treatment the fungus had disappeared. Held describes the 



1 Chuard and Ettli believing that phosphuretted hydrogen may aid to a great ex- 

 tent the insecticide action of calcium carbide, prepared calcium phosphide, CagPg, 

 which is decomposed by water into lime and phosphuretted hydrogen, so as to test it 

 comparatively against cnlcium carbide. 



