February 14, 1890.
Many thanks for your valuable note. I may say in passing that the specimen of "Ruby Madder" sent by Mr. Laurie appears to me to be inferior in brilliancy to both the Rose Madder and the Madder Carmine furnished by Messrs. Roberson; and I have no reason to doubt that the latter colours are perfectly trustworthy.
It will give me great pleasure to receive the dedication of your book, which I look forward to seeing with pleasure, and using with profit.
May 19, 1890.
Many thanks for your note, which seems to open up an interesting point. I gather from what you say that the mode of manufacture of a colour may affect its drying properties over a range extending from drying very slowly to drying very rapidly; and I shall be much interested in hearing what your experiments lead to under this head.
January 30, 1891.
Many thanks for your letter. I see that I had better wait for a final opinion until the few months have expired which you still require as tests of permanence. Meanwhile, I am a little unhappy to see in the case of colour after colour the expression "semi-permanent." I do not quite know what that means. Let me know at your leisure whether it means permanent under certain conditions, and, if so, what; or merely in a general way that the pigment stands, but only pretty well. The Rosso Saturno I quite understand is to be set aside.