of the exposure must vary according to the strength of the acid
and copper requires stronger acid and higher exposure than steel.
My plates were exposed about 13/4 minutes. The best way is
[illegible] a spoiled plate each time. By pouring off the
acid and stopping out the lights- very beautiful effects can
be produced but I have not attempted this yet.
The priciple precautions are to spread the ground evenly
and securely- it must be neither too hot nor too cold
I had a good many failures in spreading grounds;
One must also be taken not to scratch the ground- or
there will be some engraving on the plate not desired.
and the acid should be watched carefully and not left
in too long. The [illegible] and graver are useful in
[illegible] after the plate is etched. New grounds
can be spread and addition made as often as necessary.
Should you come to Davenport I can show you all the
[illegible] much better than I can describe it- and in less time.
It is the ost satisfactory mode of illustration I know of
The whole outfit costs less than $5. The plates (8 [degrees]) cost about
$15 per 1000 for paper and printing. I obtained the materials from
The Franklin Bank Note Co. 107 Liberty St. New York.
It was a great pleasure to me to meet you and [illegible]
in Des Moines- and hope I may have the pleasure of
meeting you more frequently hereafter.
One subject that I should have liked to have [illegible]
to you more about- is the matter of State Entomologist- The
bill introduced by [illegible] is a copy of the ILlinois laws
of 1867 under which Mr alsh was appointed [illegible] naming
the Agr Call. as depository of the collections I feel much interest
in having this or some other bill as good or letter go into effect.
I learn from Mr. Riley that he would accept the position
if it is offered to him and the salary is reasonable- not less
than $2000- I dont suppose there is any one in the U.S. better
qualified for the positiona and I hope Iowa will have the wisdom
to make this appropriation (instead of the $50000 for grasshopper [illegible])
Mr Fosters bill was reported back to the senate by the
Agr. Comm. adversly- and has now been referred to the Agr. College
Comm. where I hope it will undergo such changes as will
make it acceptable to the legislature [illegible] and to Mr Riley. You
know what is to be done to get it through better than I
do- but if you can do anything more pelase let me know
I should like very much to learn your views upon this
matter and will [illegible] write you to the best of my ability
If you wish any further information about the [illegible]
and [illegible] or better make us a visit in Davenport
With best regards
Truly your friend
J Duncan Putnam
