"_St. James's Terrace, February 10th, 1880._
"Dear Sir,--I have great pleasure in sending you for the purpose of your lecture some of my now ancient photographs. They show the early struggles which we had to make. The mounted drawings were all made with the _ammonia nitrate_ of silver; I send samples of the paper used. In general the paper selected contained chloride enough to form ammonia chloride. I send samples of unused paper, procured in 1839--some salted afterwards.
"All these drawings (which are dated) have been preserved by the hyposulphite of _lime_ (not soda). The hypo of lime does not form a definite compound with silver, like soda; hence it is easily washed away, and this is why the drawings are tolerably preserved after forty years. All are on plain paper. Ammonia nitrate does not answer well on albumenized paper. The art of toning by gold was not known in those ancient days, but the faded drawings on _plain paper_, as you will see, admit of restoration, in dark purple, by placing them in a very dilute solution of chloride of gold, and putting them in the dark for twenty-four hours. The gold replaces the reduced silver and sulphide of silver. I send you the only copy I have of my photogenic drawing. Five hundred were printed, and all were sold or given away. Please take care of it. The loose photographs in red tape are scenes in Egypt and Greece, taken about 1850 from wax-paper negatives (camera views) made by Mr. D. Colnaghi, now English Consul at Florence. If you can call here I shall be glad to say more to you on the matter.--Yours truly,
The above was the last of many letters on photographic matters that I had received from Dr. Taylor, and the last time I had the pleasure of seeing him was when I returned the photographs and pamphlet alluded to therein, only a short time before his death. Dr. Taylor never lost his interest in photography, and was always both willing and pleased to enter into conversation on the subject. He had worked at photography through all its changes, despite his many professional engagements, from its dawn in 1839, right up to the introduction of gelatino-bromide dry plates, and in 1879 he came and sat to me for his portrait on one of what he called "these wonderful dry plates," and watched the process of development with as much interest as any enthusiastic tyro would have done, and I am proud to say that I had the pleasure of taking the portrait and exhibiting the process of development of the latest aspect of photography to one of its most enthusiastic and talented pioneers.