322 Application of Photography to the Self-registration 
the position of the observer enables him to procure constantly, 
fresh supplies of newly distilled fluid, he must expect trouble 
from this source. It has more than once happened that the resin 
about the wick and surface of the lamp has conducted the flame 
to the whole body of the camphine, which then burns with vio- 
lence, but this ought not to occur if the lamp is kept clean ; a 
more common inconvenience is its smoking, which occurs when 
the wick is too long, or the burner too high or too low relatively 
to the fixed diaphragm; great nicety is required in these points; 
but with bad camphine the utmost care can scarcely give security 
from the annoyance. Upon these grounds, Mr. Brooke, as already 
remarked, has recently turned his attention to devising a substi- _ 
tute, and by heightening the sensibility of the paper, has succeed- 
ed in producing good results with oil lamps. Gas, it is believed, 
has not been tried; where at command, it will probably prove 
by far the most convenient and effectual source of light. 
The paper at present used for the register is prepared expressly 
for the purpose, the pulp being carefully freed from acid, alkaline, 
or saline substances. Where this cannot be procured, it should 
be the best highly glazed paper, not recently made, of the ordinary 
letter size before doubling, free from lime and other impurities, and 
of fine fibre. A r called Whatman’s yellow wove folio post 
procurable from importers in Canada, and bearing the date 1842, 
been found to answer remarkably well. It is prepared as 
follows. 
(1.) Dissolve five grains of fine isinglass in one fluid ounce of 
distilled water; the water should be poured boiling on the isin- 
glass, and then set before the fire, and stirred occasionally until 
the latter is dissolved ;_ perhaps this will require ten or fifteen min- 
utes. Asa portion is lost by evaporation, and afterwards in filter- 
ing, It Is convenient to increase the quantity of both by one half, 
that is, to take an ounce and a half of water, and seven or eight 
grains of isinglass: while this is dissolving, weigh out twelve 
grains of the bromid and eight of the iodid of potassium, put 
both salts into a deep glass, such as a large wine glass. Extreme 
nicety in the quantities is not required, the effects having been 
the bromid, and from two to eight grains of the iodid. ‘The 
isinglass being sufficiently dissolved, filter one fluid ounce 
quantity on the salts, through white blotting paper or filtering 
paper. . The salts may be stirred with a glass stick, and the solu- 
tion then set aside until cold. 
inches long, by four and three-quarters wide: if two os 
vin 
marked one side, for distinction secure the paper, with the un- 
marked side upwards, by a pin at each comer, toa clear pine 
