18 
not settled by any means. For this reason alleged cases of poisoning 
with copper should receive the most careful investigation. 
We presume no one will deny that copper in large or even moderate 
doses is unwholesome. Looking at the question from this standpoint 
let us consider the second part of our subject, 7. e., Are the salts found 
in sufficient quantity in connection with properly sprayed fruit at the 
time of harvest to cause injury to health? At this point it may be well 
to add that all our remarks apply to the Bordeaux mixture, which con- 
tains about twenty times as much copper as the ammoniacal solution, 
the only additional fungicide worthy of consideration on account of its 
extended use. 
According to Gauthier, professor of chemistry of the faculty of medi- 
cine, Paris, an adult can absorb daily for a period of several weeks 
without ill effects from 0.2 to 0.5* gram of copper sulphate, or blue 
vitriol. Five-tenths of a gram is usually considered the maximum 
amount that may be absorbed for any length of time without injury to 
health, although cases are on record where as high as 2, 3, and even 
4 grams have been absorbed for a number of days in succession without 
any ill effects whatever. Some recent French investigations have shown 
that a dog can absorb from 15 to 25 grams of copper sulphate without 
injury. Sheep have been fed 43 grams per day for several days in suc- 
cession without any noticeable derangement of the system. 
At this point we are confronted with a somewhat complex chemical 
question which makes it difficult to obtain results strictly comparable. 
The Bordeaux mixture, as elsewhere shown, is made by the addition of 
lime to a solution of copper sulphate. According to recent investiga- 
tions, the reaction is an exceedingly complicated one, the details of 
which are unnecessary here. It has generally been accepted that the 
mixture as sprayed upon the vines consists for the most part of copper 
hydrate, which upon drying becomes an insoluble compound. We have, 
therefore, first of all the question to consider whether the hydrate is 
as likely to prove injurious to health as the sulphate in solution. No 
direct investigations upon this point have, so far as we know, been made. 
It has been shown, however, that doses of copper four to five times 
greater can be administered in an insoluble than in a soluble state. 
The question now briefly stated resolves itself into this: May we, with- 
out assuming too much, use the facts bearing on the harmfulness or 
harmlessness of copper sulphate when considering copper hydrate and 
copper oxide? We believe that this assumption is not only admissible 
but is erring upon the safe side; in other words, that if an adult can 
safely absorb 0.5 gram of copper sulphate a day without injury, he may 
with much less fear of ill effects absorb the same quantity of copper 
hydrate and copper oxide. In fact,as regards the ill effects of the 
latter, hygienically considered, there is a great deal of evidence which : 
will be considered later. 
—_——__ 
*1 gram equals 15.498 grains. 
