Sept. 10. 1853.] 



NOTES AND QUERIES. 



253 



If more of the chloride than above specified be 

 added, it will cause the plate to blacken all over 

 during development, before the extreme lights are 

 fully brought up. 



My developing agent is made as follows. Take 



Distilled water - - - - 10 oz. 

 Pyrogallic acid - - . - 6 grs. 

 Formic acid - - - - - 1 oz. 



The latter is not to be the concentrated acid, but 

 merely the commercial strength. These, when 

 mixed, form so powerful a developing agent, that 

 the picture is brought out in its full intensity, 

 almost instantly, while at the same time all the 

 deep shades are quite unaffected, and the half- 

 tones come out with a brilliancy I have never 

 seen before. 



Another excellent developing agent is composed 

 as follows. Take 



The formic acid is also a most capital addition to 

 the protonitrate of iron, and either this or the 

 former liquid produce most brilliant positives, 

 leaving a tine coating of white dead silver. I may 

 also make mention of the improYement I have 

 made in the albumen paper, which consists in the 

 introduction of the chloride of barium into the albu- 

 men, in place of chloride of ammonium or chloride 

 of sodium. Take 



Water - 

 Albumen 

 Chloride of barium 



- 6 oz. 



- 6 oz. 



- 7i dr. 



Whip these up, till they are converted entirely 

 into a white froth ; when this has settled into a 

 liquid, pour it into a tall jar, and allow the pre- 

 cipitate, which will then separate, to settle com- 

 pletely, and strain the supernatant liquid through 

 fine muslin. The paper, being laid on the surface 

 of this fluid for a space of from five to ten mi- 

 nutes, may be taken off and hung up by a crooked 

 pin to dry, and then ironed. It is to be sensitized 

 with nitrate of silver, 120 grains to the ounce of 

 water. The setting liquid I use is prepared ac- 

 cording to the formula given by me in Vol. vii., 

 p. 534. of your journal, except that I prefer to 

 use half to one grain of pyrogallic acid, and 120 

 grains of chloride of silver. This paper must be 

 soaked for a few minutes or so in rain water, after 

 being printed, before being placed in the hypo. ; 

 the presence in the water of any salt seems to de- 

 stroy the tone of this paper. 

 Florian, Torquay. 



Muller's Processes — Sisson's Developing Solu- 

 tion. — I am glad to find that I have called the 

 attention of your photographic correspondents to 



Mr. Muller's process, as detailed in The Athenceum 

 of Nov. 22, 1851, which seems to have been 

 strangely overlooked and neglected. As your 

 correspondents have Induced you to reprint the 

 article, perhaps you will also yield to my request, 

 and reprint an article from the same journal of 

 later date (Jan. 10, 1852) containing another 

 process, more economical and more sensitive than 

 the other, invented also by Mr. Muller, and the 

 value of which I have proved. In that, as in the 

 other, there is no developing agent required. To 

 save time I have copied from my note-book the 

 article itself, and append it to this communica- 

 tion. 



A photographer of several years' standing in- 

 forms me that my developing solution produces 

 excellent negatives upon glass, and that he has 

 been trying it as a bath with success. He writes 

 me : — "I use your developing solution for nega- 

 tives only ; and by using a very small opening, 

 say about ■~^i\\?: of an inch diameter, single achro- 

 matic lens, I have produced negatives in one 

 minute, which print most beautiful bright positives. 

 The views I have taken and developed with your 

 solution were without sunshine, the sky very 

 cloudy, three o'clock p.m. The collodion was pre- 

 pared by Messrs. Knight & Son." 



Since I received his letter I have tried a nega- 

 tive so developed, with the best success; and I 

 attribute the success to the fact that you may go 

 on developing with that solution any length of 

 time almost, without any fear of spoiling the 

 negative, thus getting thickness of deposit ; and 

 that the deposit on pictures taking so long a time 

 to develop has a very perceptible yellow tinge, 

 which, like the gold in Professor Maconochie's 

 method (detailed in Photographic Journal for this 

 month), stops the chemical rays. 



J. Lawson Sisson. 



Edingthorpe Rectory. 



" Patna, India, Nov. 9, 1851. 



" Plain paper is floated on a bath of aceto- 

 nitrate of silver, prepared of 25 grs. of nitrate of 

 silver, 1 fluid oz. of water, 60 minims of strong 

 acetic acid. When well moistened on one side, 

 the paper is removed, and lightly dried with blot- 

 ting-paper ; it is then placed with the prepared side 

 downwards on the surface of a bath of hydriodate 

 of iron (8 grs. of the iodide in 1 oz. of water). It 

 is not allowed to remain on this solution, for if this 

 were the case it would become almost insensitive. 

 The silvered surface must be simply moistened 

 with the hydriodate — the object being to get a 

 minimum quantity of it diffused equally over the 

 silvered surface. The photographer accustomed 

 to delicacy of manipulation will find no difiiculty 

 in this. While still wet the paper is placed upon 

 a glass (face downwards), and exposed in the 



