Although I was disappointed to find that the Augustine returned without you, yet I think that you acted quite rightly in staying until the Jerome returns, as you could not get any results whilst on board. I only hope that your health will have been good, and that you will have enjoyed your stay at Pará, and that when you return in August we may have to work out plenty of interesting results.
I send per the Jerome a second bottle of silver solution, and some more salted paper, as you may possibly be out of both. I also enclose two or three fixed strips, but not calibrated. These, in case you are out, may be used, carefully preserved and calibrated, on your return. They must be carefully marked before using and notice taken in the book of the marks on each strip when employed.
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Your carbonic acid observations are very interesting: you seem to have settled Lewy completely, and I hope you will get some more experiments made on your return voyage.
Could you not manage to make several series of daily observations (photochemical) on your return voyage? It would not much matter if the surface was not perfectly horizontal always, and you could use your pendulum concern to steady the exposed paper to a certain extent. Perhaps your ship does not give you a sufficiently free horizon. However, you will do what is possible.
Your meeting with Agassiz was very fortunate, and I was glad to hear that the other friends whom you found were likely to prove agreeable.
We have not much news to send you. The book [“Lessons in Elementary Chemistry”] is not yet out. I have this day, however, corrected the last proofs of the Index, and I fully expect that it will be ready (and I hope a great number sold!) before you arrive here.
My new assistant [Mr. Francis Jones] is a very careful and accurate worker. He has with great care determined the atomic weight of vanadium by the loss of weight of VO₃ in hydrogen, and curiously enough gets exactly Berzelius’s number of 68·5! This in two experiments on large quantities. We are now preparing pure chloride to try again whether we get 67·4 (your number), and we have got hold of some very queer reactions, which I can only understand either by the presence of another metal having the same (or nearly) atomic weight as Va, or else by the existence of an isomeric (solid) modification of the chloride. However, time, I hope, will show.
My lecture on June 1st at the Royal Institution will, of course, be shorn of some of its interest as I cannot tell them how much chemical light there is in the tropics, but I hope to have enough to make an interesting hour, and have got some nice experiments to illustrate the opalescence of the atmosphere.
My wife tells me to remind you to be so good as to bring her something tropical—some birds’ skins would do or anything you see or fancy. Only no monkeys, if you please, for me! I hate the animals.