EDWARD ELSWORTH. 129 
unchanged to the present day, although ‘innumerable 
improvements ’’ have been suggested, tried, abandoned 
and returned in new form to vex the photographer. 
AS a wet process, it is still used to a limited extent, 
and we must say of it that it has given us some of the 
most beautiful photographs which have ever been made, 
and asa method for making lantern transparencies is 
still unrivalled. For general purposes, it has always had 
great disadvantages. Great care has to be exercised in 
the cleaning and preparation of the plates. They must 
be used while still in a wet state, and must be developed 
as quickly as possible after exposure, and before the sur- 
face has time to dry. 
These drawbacks soon stimulated a great many efforts 
on both sides of the Atlantic to overcome them, and va- 
rious methods were employed by some to produce dry 
plates which would keep until wanted for use; while 
others devoted themselves to the development of pro- 
cesses for keeping the collodion plates moist. The only 
successful attempt in either direction which seems to 
have been made prior to 1866 was made by Dr. Hill Nor- 
ris, an Englishman, who, by a process which was kept 
secret, produced dry plates which had good keeping 
qualities, and were nearly as rapid in action as the wet 
plates generally used. 
Between 1866 and 1879, many improvements in making 
collodion dry plates were made, but the wet plate process 
held its own in the studio. Meanwhile, a host of chem- 
ists and photographers, both in Kurope and America, 
were striving to utilize some other substance than collo- 
dion as the basis of a photographic film, as most if not 
all the dry plates made had to be sensitized by immersion 
in a silver bath. 
Attention had already been called to gelatine by Le 
Gray, and most of the experiments were made with that 
substance. The result was the gelatine bromide dry 
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