> Do you have any info about how photgraphers/chemists in the Old Days
> made dichromate compounds? That sort of information is not in the
> chemistry library.
>
J.W. Mellor's Comprehensive Treatise on Inorganic and Theoretical
Chemistry (1931) vol. 11 seems to provide a pretty comprehensive source of
this sort of information. See also Sir Edward Thorpe's Dictionary of
Applied Chemistry (1921), vol 2, pp. 240-241 or Marvin J. Udy's Chromium
(1956). I don't have the chemical background to deal with this and am more
interested in the links between discovery, manufacture and use. Like
iodine and bromine, the discovery of chromium in 1797 and its increasing
availabilty formed part of the advances in chemistry that made photography
possible.
Most 19th century photographers probably wouldn't have made their own
dichromates. Photographic applications must have represented only a small
sector of a reasonably large commercial market for pigments (chrome
yellow, etc.) and other applications in the dyeing and later tanning
(1858, commercialized by 1884) and other industries. Metallurgical uses of
chromium (its most important application today) were developed in the 19th
century but didn't come into much use before the early years of this
century. Techniques for roasting chromite (or chrome iron ore) with lime
and potash were developed and improved from as early as 1800, most
importantly by the substitution of potassium carbonate for potassium
nitrate.
The major pioneer was the chemical manufacturer Andreas Kurtz, a former
pupil of the discoverer of chromium, the French chemist L. N. Vauquelin.
Kurtz emigrated to England, establishing a soap factory in London in 1816,
and moved to Manchester in 1822, where he began producing potassium
dichromate at the premium price of 5 shillings a pound (competition and
cheaper ore gradually forced the price down). Kurtz then moved to
Liverpool where from 1831 to 1838 he experienced a certain amount of
success with his chrome colours, or so the story goes after Princess
Charlotte had her carriage painted with Kurtz' chrome yellow - the first
yellow cab. Poisonous food colours must have also been pioneered around
this time - when The Lancet launched a campaign against them in 1855 the
colour in yellow sugar confectionery came from lead chromate.
Other pioneers in the industry were John and James White, Limited, of
Glasgow, who started as soap manufacturers in 1810 and in 1820 began
making potassium dichromate. Ammonium dichromate was added in 1884,
and by the turn of the century the firm was a major general chemical
manufacturer.
In the US Isaac Tyson began producing chrome colours and potassium
dichromate in 1845 from local ore in Baltimore (previous attempts in 1828
and 1833 failed). In 1860, just before the outbreak of the Civil War, most
chemicals were still imported from Britain, but the industry gradually
expanded. A second dichromate plant was set up in Philadelphia in 1882; it
eventually took over the Tyson Baltimore works; two other firms began
making dichromate in 1897 and 1902.
"Chromate of potash" must have already been widely available and fairly
cheap when Mungo Ponton first used it for photographic purposes in 1839:
"Its great recomendation is its cheapness and the facility with which it
can be prepared. The price of bichromate of potash is 2s.6d. per lb
whereas of the nitrate of silver only half an ounce can be obtained for
that sum" ("Notice of a cheap and simple method of preparing paper for
photographic drawing, in which the use of any salt of silver is dispensed
with," Edinburgh New Philosophical Journal 27 (July 1839) 169-171. Eder
credits Gustav Suckow with discovering the light sensitivity of potassium
dichromate with organic substances (sugar) in 1832, but it seems his work
was generally unknown. Ponton probably didn't realize the process worked
because his paper sized with gelatin; the following year (1840) Edmond
Becquerel noted the importance of the presence of organic matter (starch
paste). Talbot in 1852 noted the solubility of chromated gelatine after
exposure to light, a short time later (1855) Poitevin laid the foundations
for collotype and carbon printing (Pouncy, Fargier and Blair all
contributed until the process was patented by Swan in 1864 - see Luis
Nadeau's History and Practice of the Carbon Process or William Crawford's
section on dichromated colloids in Keepers of Light for a more
comprehensive treatment of all this).
Here are a few more references from my reading of 19th century
photographic journals from around 1864. They also provide a rich source
of cautionary tales and other horror stories, if anybody doubts the
potential danger of the "chromate disease."
Dr. T. L. Phipson "Notes on Chromium" The Year-book of Photography and
Photographic News Almanac 1878, pp. 43-46.
If you can't read German, J. M. Eder's treatise on reactions of chromic
acid and chromates with organic matter was translated and serialized in
the Photographic News in 1878 (172, 183, 464, 471, 488, 520, 530, 555,
573, 578, 609) and 1879 (1, 19, 26, 40, 100, 232); see also the BJP 6 June
1879 p. 271, July 4 p. 318, 8 Aug. p 378. Eder only periperially touches
on different chromates (see PN 1878, p. 555).
Patents for improvements in the manufacture of chromates and bichromates
are noted in the BJP 9 Jan 1885, p. 29 and 30 Jan., p. 75.
BJP 21 Jan. 1887 p. 35 notes John Mercer's introduction of the use of
chromium for dyeing when potassium bichromate was half-a-guinea an ounce;
in 1887 it was 100 times cheaper.
Philip Jackson
pjackson@nla.gov.au