122 Regent S^{t <1>}
3 April 1850

To H F Talbot Esq^r

Sir

I have asked Minton to make haste with the “double-bodied” slabs referred to in your last note. In a day or two I will send you the result of some experiments relating to the conservation of the positive pictures I have been perfecting the plan for practical every-day purposes. I have ground down one of the last slabs & find cavities within I have not yet learned whether it was a prep ar^ed slab I employed If I may suggest what I think I would detail the process for firing, in the specification, without giving reasons for what is done

This will leave critics less ground for attack Let them find out the rationale of the process. My reason for this caution is the uncertainty about the action of Hydrosulphate of Ammonia as diffused in the Atmosphere. I will speak more of this in a day or two when I send you some pictures. – There may be several reasons given for doing a certain thing you may not wish to tell them all & yet if you omit any somebody may guess the omitted one & claim to have made a discovery. If all reasons be omitted this will be avoided

I remain Sir Your obed’ Serv^t
T A Malone

Our pictures with experiments are shown twice a day at the Polytechnic in a chemical lecture. This is a good advertisement

[envelope:]
H F Talbot Esq^r
Lacock Abbey
Chippenham

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Notes:

1. 122 Regent Street, London: base of Nicolaas Hennemans’ Talbotype or Sun Picture Rooms, later the firm of Henneman & Malone, photographers to the Queen.