134 



NOTES AND QUERIES. 



[No. 224. 



PHOTOGRAPHIC CORRESPONDENCE. 



Dr. Mansell having forwarded to me for publication 

 the accompanying account of his mode of operation, I 

 have much pleasure in laying it before the readers of 

 " N. & Q. ;" because my friend Dr. Mansell is not 

 only so fortunate in his results, but is one of the most 

 careful and correct manipulators in our art. The pro- 

 portions which he recommends, and his mode of ope- 

 rating, are, it will be seen, somewhat different from 

 those hitherto published. In writing to me he says : 

 " I make a point of making a short note in the evening 

 of the day's experiments, a plan involving very little 

 trouble, but of great service as a reference." If all 

 photographers would adopt this simple plan, how much 

 good would result ! Dr. M. complains to me of the 

 constant variation he has found in collodion ; (with 

 your permission, I will in your pages furnish him, and 

 all your readers, with some plain directions on this 

 point) ; and he has given me some excellent observ- 

 ations on the " fashionable " waxed-paper process, in 

 which he has not met with such good results as he had 

 anticipated ; although with much experience which 

 may some day turn to good account. Dr. Mansell 

 concludes with an observation in which I entirely con- 

 cur, viz. " That the calotype process is by far the most 

 useful ; and I find the pictures it gives have better 

 effect than the wax ones, which always to me appear 

 flat, even when they are not gravelly." 



H. W. Diamond. 



The Calotype on the Sea-shore. — The great quan- 

 tity of blue light reflected from the sea renders calo- 

 typing in its vicinity much more difficult than in the 

 country ; the more distant the object, the greater depth 

 has the blue veil which floats over it, and as a conse- 

 quence of this disproportion, if time enough is given 

 in the camera to bring out the foreground, the sky be- 

 comes red, and the distance obscured. After constant 

 failures with papers iodized in the usual manner, I 

 made a number of experiments to obtain a paper that 

 would stand the camera long enough to satisfy the 

 required conditions, and the result was the following 

 method, which gives an intensity of blacks and half- 

 tones, with a solidity and uniform depth over large 

 portions of sky, greater than I have seen produced by 

 any other process. Since I adopted it, in the autumn 

 of 1852, I have scarcely had a failure, and this success 

 induces me to recommend it to those who, like myself, 

 work in highly actinising localities. 



The object of the following plan is to impregnate 

 the paper evenly with a strong body of iodide of silver. 

 I prefer iodizing by the single process, and for this 

 purpose use a strong solution of iodide of silver, as the 

 paper when finished ought to have, as nearly as pos- 

 sible, the colour of pure iodide of silver. 



Take 100 grains of nitrate of silver, and 100 grains 

 of iodide of potassium *, dissolve each in two ounces of 



[* Having lately prepared this solution according 

 to the formula given by Dr. Diamond (Vol. viii., 

 p. 597.), in which it required 650 grains to dissolve 

 the 60-grain precipitate, we were inclined to think our 

 correspondent had formed a wrong calculation, as the 

 difference appeared so little for a solution more than 



distilled water, pour the iodide solution into the nitrate 

 of silver, wash the precipitate in three distilled waters, 

 pour off" the fluid, and dissolve it in a solution of iodide 

 of potassium, about 680 grains are required, making 

 the whole up to four ounces. 



Having cut the paper somewhat larger than the 

 picture, turn up the edges so as to form a dish, and 

 placing it on a board, pour into it the iodide solution 

 abundantly, guiding it equally over the surface with a 

 camel-hair pencil ; continue to wave it to and fro for 

 five minutes, then pour off the surplus, which serves 

 over and over again, and after dripping the paper, lay 

 it to dry on a round surface, so that it dries equally 

 fast all over ; when almost dry it is well to give it a 

 sight of the fire, to finish off those parts which remain 

 wet longest, but not more than just to surface dry it. 



Immerse it in common rain-water, often changing it, 

 and in about twenty minutes all the iodide of potash 

 is removed. To ascertain this, take up some of the 

 last water in a glass, and add to it a few drops of a 

 strong solution of bichloride of mercury in alcohol, the 

 least trace of hydriodate of potash is detected by a pre- 

 cipitate of iodide of mercury. A solution of nitrate of 

 silver is no test whatever unless distilled water is used, 

 as ordinary water almost invariably contains muriates. 

 The sooner the washing is over the better. Pin up 

 the pap.er to drip, and finish drying before a slow fire, 

 turning it. If hung up to dry by a corner, the parts 

 longest wet are always weaker than those that dry first. 

 When dry pass a nearly cold iron over the back, to 

 smooth it ; if well made it has a fine primrose colour, 

 and is perfectly even by transmitted light. 



To excite the paper, take distilled water two drachms, 

 drop into it four drops (not minims) of saturated so- 

 lution of gallic acid, and eight drops (not minims) of 

 the aceto-nitrate solution; mix. Always dilute the 

 gallic acid by dropping it into the water before the 

 aceto-nitrate ; gallate of silver is less readily formed, 

 and the paper keeps longer in hot weather. If the 

 temperature is under sixty degreesj use five drops of 

 gallic acid, and ten of aceto-nitrate ; if above seventy 

 degrees, use only three drops of gallic acid, and seven 

 of aceto-nitrate. The aceto-nitrate solution consists of 

 nitrate of silver fifty grains, glacial acetic acid two 

 drachms, distilled water one ounce. 



Having pinned the paper by two adjacent corners 

 to a deal board, the eighth of an inch smaller on each 

 side than it is, to prevent the solutions getting to the 

 back, lay on the gallo-nitrate abundantly with a soft 

 cotton brush (made by wedging a portion of fine cotton 

 into a cork) ; and keep the solution from pooling, by 

 using the brush with a very light hand. In about two 

 minutes the paper has imbibed it evenly, and lies dead ; 

 blot it up, and allow it to dry in a box, or place it at 

 once in the paper-holder. For fear of stains on the 



one-third stronger. We found upon accurately follow- 

 ing Dr. Mansell's instructions, that it required 734 

 grains of iodide of potassium to effect a solution, whilst 

 we have at the same time dissolved the quantity recom- 

 mended by Dr. Diamond with 598 grains. This little 

 experiment is a useful lesson to our correspondents, 

 exhibiting as it does the constantly varying strength of 

 supposed pure chemicals. — Ed. " N. & Q-"] 



