Cotton. 3 drachms. Iodide of cadmium. 65 grains. Ammonium iodide. 25 " Bromide of cadmium. 19 " Ammonium bromide. 11 " Alcohol. 15 ounces. Ether. 15 " The plate thoroughly cleaned and coated with the collodion is now transferred to a bath, as follows: Nitrate of silver (common) 25 grains to the ounce. Made slightly acid with nitric acid. After sensitizing, the plate is exposed in the usual way and taken to the room where pictures are ordinarily developed, and _quantum suff_. of the following poured into the developing cup to bring out the image: DEVELOPING SOLUTION. A Winchester of water, i.e. 80 ounces. Protosulphate of iron. 240 grains. Citric acid. 240 " Or the following may be used: Pyro 3 grains\ Citric acid 2 " } per ounce of water. Glacial acetic acid 30 drops / After perfect development the picture is well washed and then fixed in a saturated solution of hypo.; after which it is thoroughly washed. It will now be found that the picture is not altogether satisfactory; it lacks both vigor and color. To improve matters recourse is now had to TONING. Gold. 1 grain. Water. 5 ounces. With this a very fine depth is soon attained, and a nice picture the result. Leave out the toning, and only a poor, sunken-looking picture will be the outcome; but directly the toning bath is employed richness at once comes to the fore. I have, however, known of instances where the picture needed no toning. OPAL PRODUCTION IN PRACTICE. This is still a secret with some in the profession. A limited number of workers have succeeded in bringing out good opals, and their _modus operandi_ is kept from the many. Now this is a pity, when one considers the great charm attached to a good picture on opal, with pure whites and rich blacks, and in many localities the demand that might be created for them. Apart from their beauty, another charm attaches to opals--their absolute permanence; and this, it must be allowed, is no trifle. What, in fact, can be more painful to the worker who values his work, and sets store by it, than to feel it must ere long fade and pass into oblivion! A properly executed opal will no more fade than the glass pictures so common at one time, and which, wherever taken care of, are as perfect now as they were when first taken. Now, excellent pictures are to be made on opals by means of emulsion; but I propose first taking the transfer method (mainly applicable to ground opal and canvas) as given above for pottery, since in practice it is found very ready, easy of manipulation, and safe. The details are much the same as above, and necessitate double transfer.