186 



NOTES AND QUERIES. 



[No. 173. 



ners. I will just enumerate a few of the appear- 

 ances with which I have been troubled, and trust 

 that they may elicit from other operators an ac- 

 count of some of their instructive failures. I will 

 premise, as an answer to a former Query respect- 

 ing the cost and description of lenses, that I ob- 

 tained mine of Mr. Goddard, now of Jesse Cottage, 

 Witton, Middlesex. They are combination-lenses, 

 two inches and a quarter in diameter (achromatic) ; 

 the front lens can be used singly for views, pro- 

 ducing a picture nearly seven inches square, but 

 when combined covering four inches. For these, 

 with brass mounting, I paid less than Si. : a single 

 lens, the same diameter, would be about 11. They 

 work to focus, cover flat, and define well, producing 

 pictures equal to the most expensive. 



I have usually preferred Mr. Archer's collo- 

 dion, as the most certain and cleanest. The silver 

 bath is composed of thirty grains nitrate of silver 

 and two drops of nitric acid to each ounce of dis- 

 tilled water. An even film may be obtained by 

 the following means : — Represent the plate ,of 

 glass by the following figure : 



Hold the plate with the left hand at 1, pour a 

 body of collodion in the centre : tilt towards 1 

 (being careful not to let it touch the thumb), in- 

 cline towards 2, run into 3, and pour off at 4 : 

 then hold the plate vertically (resting the corner 

 4 on the neck of the collodion bottle) to drain : 

 incline it first to the right and then to the left, 

 repeating this several times until the ridges are 

 removed. By these means an even film may be 

 produced, without a thick ridge, from 2 to 4. 

 The time it may be left before plunging into the 

 silver bath will depend on the temperature (about 

 half a minute). Dip evenly into the bath, lifting 

 up and down to allow of the evaporation of the 

 ether : the film will also saturate more rapidly. 

 When the greasy appearance is gone, it is ready 

 for the camera. Sometimes the film is nearly 

 transparent and bluish, not having sufficient 

 iodide of silver ; or it may contain too much 

 iodide, the greater part flaking off" in the bath, 

 leaving the collodion with very little, and that 

 patchy ; or from being placed in the bath too 

 quick, the lower corner will present a reticulated 

 appearance, which of course renders it useless. 



Having exposed the plate the necessary time, 

 the next step is the development. The solution I 

 usually employ is prepared with protosulphate of 

 iron. I do not find distilled water absolutely ne- 

 cessary (during the summer months I fancied the 

 tones were improved by using ordinary water, 

 perhaps from containing a little lime), and the 

 acetic acid is not glacial, but a description termed 



Beaufoy's, much less expensive. The proportions 

 are — 



Water - . . 



Acetic acid - - 



Protosulphate of iron - 

 Nitric acid 



- 2 ounces. 



- 1 drachm. 



- 8 grains. 



- 2 drops. 



Mix the water and acetic acid first ; then dissolve 

 the iron ; and, lastly, add the nitric acid, which, by 

 varying the quantity, produces diSerent effects. 

 On pouring the solution over the plate, there is 

 sometimes a difficulty experienced in causing it to 

 flow evenly. Sometimes a little more acetic acid 

 in the developing solution, or, if the plate has been 

 out of the bath some time, redipping it, will pre- 

 vent this ; but if this does not remove it, and the 

 resulting picture is hard and unpleasant in tone, a 

 new bath is necessary. For positives, the resulting 

 picture is more pleasing and delicate by using the 

 developing agent rather weak. After it has re- 

 mained on sufficiently long to bring out the image, 

 the undecomposed iodide is to be removed by 

 hyposulphite of soda. I always use the same 

 solution, pouring it on and off" until exhausted. 

 Having sufficiently washed, the picture may per- 

 haps appear with many black spots, this may in 

 future be obviated by adding a little alcohol to 

 the collodion : — or it may be covered with white 

 spots ; in that case the collodion requires settling, 

 or rapidly filtrating through an old piece of loose 

 silk. Sometimes it will look all black and white 

 (a common fault with collodion positives), without 

 middle tints : by adding a little more acetic acid, 

 or an extra drop of nitric acid, to the developing 

 solution, or the addition of a few drops of ordinary 

 pyrogallic solution, this disagreeable effect may be 

 overcome. In taking portraits, it is often caused 

 by having the sitter placed with too much front 

 light. Then, again, the should-be whites of the 

 picture may be dull and greenish by reflected, and 

 red by transmitted, light. This effect I generally 

 find remedied by putting less nitric acid in the 

 developing solution. During the development, by 

 watching the colour (by holding a piece of white 

 paper underneath), this red tendency may be ob- 

 served; in that case the drawing may be preserved 

 by leaving the plate for about a minute after 

 pouring the developing agent off", and before re- 

 moving the iodide. Some change appears to take 

 place by its contact with the air ; it gradually gets 

 more opaque, and when finished, though not so 

 white as many, yet presenting an extremely rich 

 brownish-yellow tone. 



During the late dull weather, many of my plates 

 have shown a tendency to an uniform leaden- 

 looking deposit, destroying the blacks of the pic- 

 ture. A little more nitric acid in the bath will 

 sometimes overcome this, but I have not yet found 

 a sufficient remedy. During the summer months 

 I was in the habit of using double the quantity of 



