Feb. 18. 1854.] 



NOTES AND QUERIES. 



157 



printing, and the best methods of producing those 

 beautiful black tints which are so much prized ; and I 

 think that, although the processes formerly given all 

 of them produce this effect with tolerable certainty, 

 yet many operators, in common with myself, have met 

 with the most provoking failures on this head, where 

 they felt the most certain of good results. 



I do not pretend to make a collodion which is 

 different in its ingredients from that compounded by 

 others. The only thing is that I am anxious to de- I 

 fine the best proportions for making it, and to give a 

 formula which even the most unpractised operator may 

 work by. First, to produce the collodion I always use 

 the soluble paper prepared according to the method 

 indicated by Mr. Crookes, and to which I adverted in 

 • N. & Q.," Vol. viii., p. 252. Take of colourless 

 nitric acid of 1*50, and sulphuric acid of 1-60, equal 

 quantities by measure, and mix them ; then plunge into 

 the mixture as much of the best Swedish filtering 

 paper (Papier Joseph is also very good) as the liquid 

 will cover ; it must be placed in it a single piece at a 

 time. Cover the basin, and let it remain a night, or 

 at least some hours. Then pour off the liquid, and 

 wash the paper till its washings cease to taste the least 

 acid, or to redden litmus paper. Then dry it. Of 

 this paper I take 180 grains to one pint of ether, and 

 having placed them together, I add alcohol drop by 

 drop, till the ether begins to dissolve the paper, which 

 will be denoted by the paper becoming quite trans- 

 parent. I have rather increased the quantity of paper 

 to be added, as the after treatment rather thins the 

 collodion. This, when shaken up and completely dis- 

 solved, forms the collodion. To sensitize I use two 

 preparations, one prepared with potassium, the other 

 with ammonium compounds; and, contrary to what 

 many operators find the case, I find that the potassium 

 gives the most rapid results. To prepare the po- 

 tassium sensitizer, I take two bottles of, we will sup- 

 pose, 6 oz. each ; into one of thes? I put about half an 

 ounce of iodide of potassium in fine powder, and into 

 the other an equal quantity of bromide of potassium, 

 also pounded; we will call these No. 1. and No. 2. 

 I fill the bottle No. 1. with absolute alcohol, taking 

 great care that there is no oxide of amyle in it, as that 

 seriously interferes with the action of the collodion. 

 After leaving the alcohol in No. 1. for two hours, or 

 thereabouts, constantly shaking it, let it settle, and 

 when quite clear decant it off into No. 2., where leave 

 it again, with constant shaking, for two hours, and 

 when settled decant the clear liquid into a third bottle 

 for use. The oxide of amyle may be detected by 

 taking a portion of the alcohol between the palms of 

 the hands, and rubbing them together, till the alcohol 

 evaporates, after which, should oxide of amyle be 

 present, it will easily be detected by its smell, which 

 is not unlike that exhaled by a diseased potato. Of 

 the liquid prepared, take one part to add to every three 

 parts of collodion. The next, or ammonium sensitizer, 

 is made as follows. Take 



Absolute alcohol 

 Iodide of ammon. 

 Bromide of ammon. 



- 10 oz. 



- 100 grs. 



- 25 K rs. 



Mix, and when dissolved, take one part to three of 



collodion, as before. I feel certain that on a strict 

 adherence to the correct proportion depends all the 

 success of photography ; and as we find in the kindred 

 process of the daguerreotype, that if we add too much 

 or too little of the bromine sensitizer, we make the 

 plate less sensitive, so in this process. When making 

 the first of these sensitizers, I always in each case let 

 the solution attain a temperature of about 60° before 

 decanting, so as to attain a perfectly equable compound 

 on all occasions. 



In the second, or ammonium sensitizer, the solution 

 may be assisted by a moderate heat, and when again 

 cooled, may advantageously be filtered to separate any 

 sediment which may exist ; but neither of these liquids 

 should ever be exposed to great cold. 



I dissolve in my bath of nitrate of silver as much 

 freshly precipitated bromide of silver as it will take up. 

 Next, as to the printing of positives to obtain black 

 tints, the only condition necessary to produce this re- 

 sult is having an acid nitrate bath ; whether the posi- 

 tive be printed on albumen paper, or common salted 

 paper, the result will always be the same. I have 

 tried various acids in the bath, viz. nitric, sulphuric, 

 tartaric, and acetic, and prefer the latter, as being the 

 most manageable, and having a high equivalent. The 

 paper I now constantly use is common salted paper, 

 prepared as follows. Take 



Chloride of barium - 180 grs. 



Chloride of ammon. - 100 grs. 



Chloride of potassium - 140 grs. 



Water - - - - - 10 oz. 



Mix, and pour into a dish and lay the paper on the 

 liquid, wetting only one side ; when it has lain there 

 for about five minutes if French paper has been used, 

 if English paper till it ceases to curl and falls flat on 

 the liquid, let it be hung up by a bent pin to dry. 

 These salts are better than those generally recom- 

 mended, as they do not form such deliquescent salts 

 when decomposed as the chloride of sodium does, and 

 for this reason I should have even avoided the chloride 

 of ammonium, only that it so much assists the tints ; 

 however, in company with the other salts, the nitrate 

 of ammon. formed does not much take up the atmo- 

 spheric moisture, and I have never found it stain an 

 even unvarnished negative. To sensitize this paper 

 take 



Nitrate of silver 

 Acetic acid, glacial 

 Water - 



500 grs. 

 2 drs. 

 5 oz. 



Mix, and lay the paper on this solution for not less 

 than five minutes, and if English paper, double that 

 time. The hyposulphite to be used may be a very 

 strong solution of twenty to twenty-five per cent., and 

 this mode of treatment will always be found to produce 

 fine tints. After some time it will be found that the 

 nitrate bath will lose its acidity, and a drachm of acetic 

 acid may be again added, when the prints begin to 

 take a red tone : this will again restore the blacks. 

 Lastly, the bath may of itself get too weak, and then 

 it will be best to place it on one side, and recover the 

 silver by any of the usual methods, and make a new 

 bath. One word about the addition of the bromide of 



