174 Miscellanies. 
the process being in every respect so different, we cannot see that it in 
any way interferes with the position of Mr. ‘Talbot. 
We must leave this question and now proceed to analyze the claims of 
two of our countrymen, Messrs. Havell and Wellmore, who are said to have 
introduced an important addition to the process pursued by Mr. Talbot, a 
full description of which is contained in a letter to the editor of the Liter- 
ary Gazette. The first attempt of this gentleman was directed towards an 
etching, by Rembrandt, of an old man reading, and the result was a rever- 
sed fac-simile; a negro face surmounted by locks of silver; the disappoin- 
ted artist discovered that a second transfer entirely destroyed the spirit of 
the picture. To remedy this evil he had recourse to a new process, by 
which this defect was indeed removed, but the great merit of the art, name> 
ly, self-acting power, was lost. A thin plate of glass was laid on the subject 
to be copied, upon which the high lights were painted with a mixture of 
white lead and copal varnish, the proportion of varnish being increased for 
the darker shading of the picture. The next day Mr. Havell removed the 
white ground with the point of a penknife, to represent the dark etched 
lines of the original, and a sheet of prepared paper having been placed 
behind the glass and thus exposed to the light, a tolerable impression was 
produced ; the half tints had, however, absorbed too much of the vi ' 
ray, an imperfection which was remedied by painting the parts over with 
black on the other side of the glass; if allowed to remain too long exposed 
to the sun’s rays the middle tints became too dark, and destroyed the ef 
fect of the sketch; about ten minutes in a powerful sun was consid- 
ered sufficient. Another method employed by Mr. Havell was to spread 
a ground composed of white lead, sugar of lead, and copal varnish, over * 
plate of glass, and having transferred a pencil drawing in the usual man 
ner, to work it out with the etching point till it bore the appearance of @ Spi 
ted ink drawing, or in the hands of an engraver a highly finished engt® 
ving. The above process Mr. Havell made public under the impress! 
that it had been hitherto overlooked, but Mr. Talbot, hearing that he ~ 
about to apply for a patent, laid claim to the improvement as his ow, and 
not only pointed out some parts of his former memorial where it wa5 a 
tinctly mentioned, but also produced several drawings made precisely 1 
the manner described; he has also laid before the Royal Society me 
method of preparing the sensitive paper, which consists in immersINg 
in a solution of nitrate of silver, and after washing it with bromide of al 
tassium, the nitrate of silver is again applied, the preparation being 
dried by the fire between each operation; the paper thus treated 15 eX 
tremely sensitive, changing with the feeblest daylight, first to @ on 
green then to olive green, and finally to black. 
A letter to Mr. Talbot from his friend M. Biot has also been published, 
and contains many interesting experiments. After commenting 0? © 
value of the discovery, he continues—* The interest with which I viewed 
OTE ES Pr nee oe ee ee aa 
