496 I'KOCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 



seed, another at tlie bottom for discharging the seed into sacks. In 

 the system of pipes is inserted an evaporating apparatus, and a series 

 of taps. It is possible to connect any one, two or more vats with the 

 air-pump and with the evaporator. In practice it was intended to fill 

 one vat and charge it with carbon bisulphide gas. Whilst the gas is 

 acting the other vats would be filling. Allowing 10 minutes for filling 

 and discharging each vat, the turn of each for action would come round 

 in one hour's time, during which its contents would be exposed to the 

 gas. After this time the gas would be pumped over into the vat 

 whose turn for gassing had come, and a fresh dose of bisulphide added. 

 The action of the machine was perfect, and not over expensive, but 

 objections were raised to it on account of the smell created, and more 

 jiarticularly on account of the danger of explosions. The Entomo- 

 logical Section, considering that hydrocyanic acid gas was too danger- 

 ous to be used for this purpose, consequently turned its attention to 

 heat treatment. 



In the meanwhile the possibility of hydrocyanic acid gas treatment 

 as a method of killing worms in seed was advocated by a member of 

 the public and a machine was constructed at Government expense 

 by Messrs. Sulzer, of Winterthur, Switzerland. It consisted of a 

 gas generator and dryer, an air-pump, and six vats which, in contrast 

 to ours, were intended to withstand a partial vacuum. The seed was 

 likewise fed in at the top and withdrawn at the bottom. 



Experimental work with this machine in 1916 revealed an unexpected 

 weakness. At temperatures under 27°C. the gas condensed on the 

 seed, and action was imperfect. To obtain reasonable results it was 

 consequently necessary to heat the seed previous to treatment, if its 

 initial temperature was too low — a condition normal in winter. The 

 use of the machine has never advanced beyond the experimental stage. 

 Its initial cost will prevent its adoption by ginneries, as the standard 

 heat-treating machines are much cheaper both in initial cost and in 

 running expenses. 



Prior to the erection of this machine an experimental hot-air machine 

 had in 1914 been erected by Mr. Crovisier of the State Domains Adminis- 

 tration, and demonstrated in June 1914 simultaneously with our 

 carbon bisulphide machine. Although successful, it was rejected 

 on account of its great bulk and small output. It consisted of 

 a large double- walled box four metres long and sixty centimetres high 

 and sixty centimetres broad and was heated by a number of steam pipes 

 running from one end to the other. An endless canvas band, kept 

 in position by means of a leather belt at either side, ran into the box 

 at one end and out at the other, passing along a short distance above 



