WITH THE MICROSCOPE. 26l 



diy's work, to pour the nitrate bath into a clean bottle, allow it to 

 settle, then carefully decant the clear portion into the bath, after it 

 has been washed out, and filter the remainder through a washed paper 

 filter, making up the strength, if necessary, by the 5o-grain solu- 

 tion. In this way there is less likelihood of spots, pin holes or 

 deposit on the transparent shadows. This bath in winter can be 

 made stronger. 



:$3. of the Developing Solutions. Preference is given to the 

 formula containing the protosulphate of iron, or the double salt of 

 sulphate of ammonia and iron, with or without a little syrup from 

 loaf sugar added at the time of using, as recommended by Mr. Hislop, 

 though without care this will often give fogging. 



Crystallised protosulphate of iron crushed, 200 grains. 



Glacial acetic acid, 3! to 5 drachms, or, 



Beaufoy's acetic acid of 30 per cent., 10 to 15 drachms. 



The amount of 10 oz. is to be made up with pure water, then 6 or 8 

 grains of acetate of soda are to be added, and the fluid filtered. More 

 iron should be added to this developing solution in the winter months. 

 It is best when a few days old. At the time of using, to make it flow 

 freely on the surface of the collodionised plate, add of ordinary alco- 

 hol from 20 to 30 or 60 minims to each ounce of developing solution, 

 according to the condition of the bath. Its strength is often varied 

 from 10 grains to the oz. to even 50 grains in ordinary work, but in sun- 

 light negatives, it is not necessary to use more iron than in the formula. 

 The intensifying solution, useful for deepening more fully many 

 of the details brought out by the iron developer, consists of: 



No. i. Iodine, 3 grains. 



Iodide of potassium, 6 grains. 

 Water, 3 ounces. Mixed. 



No. 2. Pyrogallic developing solution, as made with acetic acid. 

 Pyrogallic acid, ii to 2 grains. 

 Glacial acetic acid, 20 minims, or 

 Beaufoy's acid, i drachm. 

 Distilled water, i ounce. 

 This is best when freshly made, or not more than a few days old. 



No. 3. Pure nitrate of silver, 30 grains. 



Distilled water, i ounce. 



No. 4. Pure nitrate of silver, 20 grains. 



Citric acid crystallised, 30 grains. 

 Dissolved in distilled water, 2 ounces. 



