4 FUMIGATION METHODS 



Speaking of the early experiences with this gas, 

 Prof. C. W. Woodwork says that previous to the 

 time of the publication of Morse's soda method, Mr. 

 Coquillett accomplished a similar diminution of injury 

 by slow generation of the gas. This Mr. Coquillett 

 accomplished by means of a generator consisting of two 

 parts: from one the sulphuric acid passed in a fine 

 stream, regulated by a stop-cock, into the other con- 

 taining dry cyanide. These facts were clearly set forth 

 by Alexander Craw in a paper before a meeting of 

 fruit growers at I,os Angeles, in October, 1887. 



The ' ' dry gas process ' ' was soon devised by Mr. 

 Coquillett. It consisted in passing the gas from the 

 generator through sulphuric acid, allowing it to come 

 in contact with the foliage. In this he used a solution 

 of cyanide. This was the situation at the time of the 

 publication of Mr. Coquillett 's first paper, cited above, 

 wherein these three processes were described quite 

 fully. He strongly recommended his last process as 

 the cheapest and most convenient; and Mr. Morse, in 

 a later paper, practically abandoned his soda method in 

 favor of the dry gas process. 



Injury to trees from the first has been a specula- 

 tion and controversy, and even now it must be con- 

 fessed that we are far from possessing sufficient data to 

 enable us to solve any considerable part of the problem. 

 The results have been very uncertain, proving that 

 there are a number of factors involved. One of the 

 earliest explanations suggested was that faulty dis- 

 tribution of the gas would tend to cause burning 

 wherever the pure or slightly diluted gas came in con- 

 tact with the leaves. Practical experience bore out 



