THE PREPARATION OF SOLUTIONS, ETC.
made all our purchases, and provided ourselves with proper dark-room accommodation, or its substitute, we have still to preparo the necessary solutions for the various operations of developing, fixing, etc., through which the plate has to pass, before we shall be really ready for work.
At the outset, and before we begin our first lesson in photo-chemistry, let me urge upon the reader the necessity of being careful and exact in the weighing out and measuring of the various chemicals used in making up the different solutions. Slap-dash guess-work will never pro duce good results in photography, and those who wish to succeed should lay the foregoing advice to heart. To the importance of cleanliness, and the avoidance of chemical contamination of any kind, I have already referred, and to this end one of the small glass measures should be reserved for the exclusive use of making up solutions. After measuring off the requisite quantity of one chemical or solution, the measure should be at once thoroughly washed under the tap, and dried with a cloth kept for the purpose.
Neither measures nor dishes should be put away dirty, or allowed to remain with waste solutions in them, for if this be allowed to occur it will be a difficult matter to again get them chemically clean. When apparatus, either glass or porcelain, gets discoloured from such a cause, its surfaces should be brushed, by means of a stiff brush, with a solution of hydrochloric acid 1 part, water 4 parts, and afterwards well rinsed in water. Brookes' soap in the case of porcelain dishes (not glass, the surface of which it scratches and dulls) will be found very useful in removing chemical stains.
The beginner may, if he so choose, though I by no means recommend him to adopt that course, purchase the solutions which he will require, all ready prepared for use, from the dealer from whom he obtained his apparatus. Such a mode of working, however, is so essentially a " rule of thumb " business, that it will probably commend itself to but few of my readers. Let the tyro, therefore, from the very outset, learn to prepare his own solutions, and so place himself in a position of independence.
We will begin work by preparing our developer. The reader, novice though he be, is probably aware that the image which is formed on the sensitive surface of the plate by exposure in the camera is not visible, but requires to undergo the process called " development " in order to make it so.
There a,re a, great many different systems of development in vogue at the present day-, each of which has its admirers ; but were I to describe them all I should only succeed in reducing the reader's mind to a state of chaos and indecision.
I propose, therefore, to describe two methods only, both of which have stood the test of time. In the first pyrogallic acid is the reducing agent, and in the second hydroquinone.
To make the solution necessary for the former, weigh out 3 oz. of sulphite of soda, place it in a clean jug, and pour over it 8 oz. of hot A-vater, stir with a glass rod until dissolved. When quite cool add the contents of the 1 oz. bottle of pyro., and, finally, 20 grs. of citric acid. Now add sufficient water to make up the bulk to 10 oz. This should be kept in a stoppered bottle, and labelled " Pyro. solution, No. 1." The pyro. solution is the true developer, but it requires the addition of an alkali in order to bring out its energy. Solutions of the fixed alkalis, potash, or soda, may be used, or liquid ammonia. In my own practice I invariably use the latter, and I advise the reader to follow my example. To make the solution, take a clean 10-oz. stoppered bottle, and pour into it 1 oz. of the strong ammonia, taking care, for the reasons already stated, not to inhale the fumes; add at once 9 oz. of distilled water—if tap water is used, the solution will probably turn milky, owing to the precipitation of car bonate of lime. Label this No. 2 "Ammonia solution : Accelerator." But ammonia used alone would cause development to proceed too rapidly, and therefore (for reasons which I shall deal with when I come to write on development) it is necessary to introduce a third substance into the developer, which is called " the restrainer." To prepare it, take another 10-oz. bottle, preferably of a different shape to the last, so that it may be readily distinguished in the dark-room, and pour into it 10 oz. of distilled water, to which add 1 oz. of bromide of potassium. Label this No. 3 " Restrainer." We now only require one more solution to complete the list necessary for the production of our negatives, and that involves the use of a chemical which is at once the greatest friend and the deadliest enemy to the photographer. Its name is hyposulphite of soda, the familiar " hypo." of the photographer, and its function is to " fix " the negative after development or, in other words, to dissolve out of the film all the sensitive silver salt which has not been acted upon by light and reduced by the developer. It is most essential to keep this substance away from all other solutions —the slightest trace of it in the developer, or in a measure, or a tray used for development, would at once spoil the results. As a large quantity of it will be used, it may be made up in bulk by dissolving in a quart of water as much of the salt as the water will take up, keeping it in a well corked bottle or jar.