Antoine Thompson d’Abbadie to Faraday   21 January 1858¹

Paris, rue Bellechasse 31 | 1858 Jany. 21

My dear Sir

Some time ago you were kind enough to inform me that your heavy glass is not to be had in England. As I am in great want of it I have tried to persuade several glass manufacturers to undertake the making of it, and at last Messrs Maes² & Clémandot³ of Paris have consented if I can be fortunate enough to obtain from you answers to the following queries for they do not like to make several trials.

1. What are the ingredients? 2 their proportions. 3. Are they melted at a low or a high heat? 4. is there any particular process (in French, tour de main) necessary to prevent the formation of Striae and the Separation of ingredients according to their density? 5. What sort of crucible was employed by you? 6. How much of the glass did you find it convenient to make at once? 7. what was the Size of the largest pure bit of your heavy glass.

I do not wish to encroach on your valuable time by requesting an answer in your own hand, but I hope that you may be kind enough to direct one of your assistants to pen the answers to the foregoing questions and send them, not prepaid, to me at rue Bellechasse 31 Paris.

It is with much reluctance that I here venture to trespass on your time, but the only frenchman who ever made glass with an index of refraction equal to 2, & even then in small quantities & impure, is now dead, & if you do not come to my help I am afraid that I must give up my plan of improvement in Astronomical instruments. I hope at all events that I may some day be able to return your preceeding kindness towards me, & remain

ever most truly yours | Antoine d’Abbadie | Correspt. de l’Institut

Professor Faraday, F.R.S. membre de l’Institut | etc etc.