598 



NOTES AND QUERIES. 



[No. 216. 



remove it, lay it upon its dry side upon a piece of 

 blotting-paper, and stroke it over once or twice 

 with a glass rod ; this as effectually expels all the 

 particles of air as complete immersion ; it is also 

 more economical, and has the advantage of re- 

 quiring much less time in the after-immersion in 

 the hypo, when it is required to remove the iodide. 

 Either pin the paper up, or lay it down upon its 

 dry side, and when it becomes tolerably dry 

 (perfect dryness is not requisite), immerse it in 

 common cold water for the space of four hours, 

 changing the water during that time three or four 

 times, so that all the soluble salts may be re- 

 moved ; often move tlie papers, so that when se- 

 veral sheets are together, one does not press so 

 much upon another that the water does not equally 

 arrive at all the surface. 



If this paper is well made, it is of a pale straw 

 colour, or rather primrose, and perfectly free 

 from unevenness of tint. It will keep good for 

 several years ; if, however, the soluble salts have 

 not been entirely removed, it attracts damp, and 

 becomes brown and useless or uncertain in its ap- 

 plication. 



Some of our oldest and most successful operators 

 still adhere to and prefer the iodized paper pre- 

 pared by the double process, which certainly 

 effects a saving in the use of the iodide of potas- 

 sium. The following is the easiest way of so 

 preparing it: — Having floated your marked sur- 

 face of the paper on a 30-grain solution of nitrate 

 of silver, and di'ied it*, immerse it for 20 minutes 

 in a solution of iodide of potassium of 20 grains to 

 the ounce, when it immediately assumes the de- 

 sired colour. It is then requisite, however, that it 

 should undergo the same washing in pure water 

 as tlie paper prepared by the single process. 



Upon the goodness of your iodized paper of 

 course depends your future success. Although it 

 is not requisite to prepare it by candle-light (which 

 in fact is objectionable from your inability to see 

 if the yellow tint is equally produced), I think it 

 should not be exposed to too strong a light ; and 

 as the fly-fisher in the dull winter mouths prepares 

 Lis flies ready for the approaching spring, so may 

 the photographer in the dull weather which now 

 prevails, with much advantage prepare his stock 

 of iodized paper ready for the approach of fine 

 weather.f 



* For this purpose, strips of wood from 1 inch to 

 1| square will he found much more convenient to pin 

 the paper to than the tape or strhig usually recom- 

 mended. Tlie pressure of a corner of the paper to the 

 wood will render it almost sufficiently adherent with- 

 out the pin, and do away with the vexation of corners 

 tearing off". 



■{• Some difference of opinion seemed to exist at the 

 reading of the paper, as to the propriety of preparing 

 iodized paper long before it was required for use, and 



Many other ways of iodizing paper have been 

 recommended which have proved successful in dif- 

 ferent hands. Dr. Mansell, of Guernsey, pours the 

 iodide solution upon his paper, which previously has 

 had all its edges turned up so as to resemble a dish ; 

 he rapidly pours it off" again after it has completely 

 covered the paper, and then washes it in three 

 waters for only ten minutes in all : he considers 

 that thereby none of the size of the paper is re- 

 moved, and a more favourable action is obtained. 

 In the experiments I have tried with the use of 

 the air-pump, as recommended by Mr. Stewart, I 

 have met with much trouble and little success ; 

 and I am inclined to attribute the very beautiful 

 specimens which he has produced to his own good 

 manipulation under a favourable climate.* 



To excite the paper take 10 drops (minims) of 

 solution of aceto-nitrate of silver, and 10 drops of 

 saturated solution of gallic acid, mixed with 3 

 drachms of distilled water. 



The aceto-nitrate solution consists of — 



Nitrate of silver - - 30 grains. 



Glacial acetic acid - - 1 drachm. 

 Distilled waterf - - 1 ounce. 



If the weather is warm, 6 drops of gallic acid to 

 the 10 of aceto-nitrate will suffice, and enable the 

 prepared excited paper to be kept longer. 



This exciting fluid may be applied either directly 



I have since received some letters from very able pho- 

 tographers who have attributed an occasional want of 

 success to this cause. I have, however, never myself 

 seen good iodized paper deteriorated by age. Many 

 friends tell me they have used it when several years 

 old; and I can confirm this by a remarkable instance. 

 On Tuesday (Dec. 6) I was successful in obtaining a 

 perfectly good negative in the usual time from some 

 paper kindly presented to me by ]\Ir. Mackinly, and 

 which has been in his possession since the year 1844. 

 I should add, the paper bears the mark of " J. What- 

 man, 1842," and has all the characters of Turner's best 

 photographic paper. It appears to be a make of What- 

 man's paper which I have not hitherto seen, and, from 

 its date, was evidently not made for photographic pur- 

 poses. 



* The paper may be iodized by pouring over it 

 30 minims of the iodizing solution, and then smoothing 

 it over with the glass rod. Care must however be 

 taken not to wet the back of the paper, as an uneven- 

 ness of depth in the negative would probably be the 

 result. 



■]• Much more attention should he paid to the purity 

 of the distilled water than is generally supposed. In 

 the many processes in which distilled water is used, 

 there is none in which attention to this is so much re- 

 quired as the calotype process. I mention this from 

 having lately had some otherwise fine negatives spoiled 

 by being covered with spots, emanating entirely from 

 impurities in distilled water purchased l>y me during a 

 late excursion into the countrv. 



