Miscellaneous. 349 



''Very well; but how do you know that any insoluble salt in the 

 Bordeaux mixture — and there are four of them — kills the fungi?" 

 "I do not knoiv, but something does, when good Bordeaux is proper- 

 ly applied." "Of course, but you can't say copper sulphate did it; 

 and since we all agree that the soluble copper sulphate does kill 

 fungi, why convert it into a lot of insolubles about which we know 

 nothing?" He had no reason for it. I then asked, ''How much 

 copper hydroxide is made from the sulphate used in the Bordeaux 

 mixture?" "Very little," said he. "Then are we not silly 

 to throw away so much soluble sulphate for so little 

 insoluble hydroxide?" "It seems so, though I have not studied 

 the dust process." "If copper sulphate kills, why not put that di- 

 rectly on the fungi?" "I suppose it would be better; at least, in 

 some respects." "Do you know of any way to do that?" "I do 

 not." "Well, I do, and we do it every time we put Sal Bordeaux 

 on a tree. And that is not all ; the sulphate is so held in suspension 

 that it is copper sulphate after the dust has been in the presence 

 of moisture three times, and how much longer, I know not; but 

 as long, I suspect, as any of the dust remains on leaf or twig. If 

 the sun comes out warm and evaporates the dew or the exudations 

 from the tree, the sulphate in the dust resumes its work as night 

 fall comes on again — a thing you can not say of the Bordeaux mix- 

 ture." 



At the hotel last night I showed the Sal Bordeaux to him and 

 others. I used the same dust I had used six days before, as well as 

 some new dust, and each yielded the copper test at once. "Well, 

 then," said he, "after your sulphate comes in contact with mois- 

 ture, hydroxide is formed, and you are in the same fix as the other 

 fellow is." "Not quite so bad," said I, "for we have already had 

 the direct and positive action of the sulphate, and that is what 

 kills." The Professor is a very busy man, but I trust he will find 

 time to take the matter up and investigate for himself. We want 

 it tested more and more. 



One point more and I am done. Last night Mr. Munson said 

 that no dry spray that he had ever seen would control mildew, 

 downy fungus, or black rot on grapes. That, no doubt, is his ex- 

 perience ; but he should confine that statement to Texas, as he does 

 the dust to such "dry spray as he had seen," and probably has used, 

 for I know o%ir dry spray will control all these, and more, too, in 

 Missouri, and I will guarantee it in Arkansas as well. 



