THE TO-M>-G PROCESS.] UNDULATORY FORCES. LIGHT PHOTOGRAPHY. 



155 



We need scarcely observe, that nothing but a really 

 good positive print is worthy of the toiling process ; 

 and more than this, it should have been printed with 

 that object in view. In giving instructions as to this 

 process, we cannot do better than quote from the Pho- 

 tographic News Almanac, in which the writer lucidly 

 points out each step. We can confirm, from our own 

 experience, the statements which lie makes ; and shall 

 presume that our previous instructions as to sensitising 

 the paper have been fully carried out. The author of 

 the paper referred to, says : 



" The printing should be effected as soon after ex- 

 citing the paper as possible : considerable over-printing 

 is generally desirable. The lights should be of a delicate 

 lavender tint, and the shadows deeply bronzed, before 

 the print leaves the pressure frame. 



" The prints should be washed in two or three changes 

 of water just before toning ; and the final washing- 

 water may have a little salt added. Long soaking 

 in salt and water renders the toning more difficult All 

 the processes in connection with printing and toning, 

 with the exception of the exposure, should be conducted 

 in the dark, or in yellow light ; and the most scrupulous 

 cleanliness, as to fingers and dishes, must be observed. 

 In regard to the latter, it is desirable that each one be 

 kept to its own purpose, and never used for any other ; 

 and the utmost care should be taken not to put the 

 fingers which have just touched the hyposulphite of 

 Into the gold solution. 



ural different forms of the alkaline gold toning 

 bath have been proposed, all of which have been prac- 

 tised with more or less success. We shall only refer 

 to those with the results of which we are familiar, and 

 can speak with personal confidence. The first is the 

 process of Mr. Maxwell Lyte, with which most pho- 

 tographers are already familiar, It stands thus : 



" Chloride of gold . . .1 grain. 

 Phosphate of soda . . .18 grains. 

 Distilled water . . . quantum ruff. 



" The chloride of gold, and phosphate of soda, should 

 bo kept in solutions of given strength say one 

 grain "f ;j"' 1 t.> an ounce of water; they can then be 

 well i .ny quantity required for use, and diluted 



with sufficient water to float the prints easily. The only 

 effect of using a large quantity of water, is to make the 

 process of toning somewhat slower, which is frequently 

 an advantage. Sufficient water tends, moreover, to 

 secure regular toning. The prints should be kept mov- 

 ing, and prevented from sticking together, or red, im- 

 perfectly-toned patches will bo the result. The water 

 used for diluting the bath may be previously made 

 warm, as it materially facilitates the process, especially 

 in cold weather. 



"The process of toning is more rapid in some cases 

 than others ; but in most cases, a few minutes from 

 two minutes to ten is sufficient. It is, in all cases, 

 desirable to allow tho print to assume a little <! 

 tint than is required in the finished picture, as a little 

 will be lost in the hypo fixing bath. If a sepia or 

 brown lie required, a decided purple tint should be 

 obtained in tho toning bath. If a decided purple be 

 desired, then the tint in the toning bath should be 

 black. 



" r'or the phosphate of soda, the bicarbonate or 

 bilxirate may be substituted, but in less proportions 

 in regard to the carbonate especially, as an excess of 

 it has a tendency to dissolve the size of the print, and, 

 in some oases, even the albumen. Five grains will, 

 therefore, be generally found sufficient ; the only object 

 being to neutralise the free acid in the chloride of 



" We have seen very fine prints produced by the 

 toning process recommended by Legray ; which in as 



H : 



" Chloride of gold .... 1 grain. 

 Erne . . . . 1 

 ,, sodium ; i.e., common salt 1 ,, 

 Distilled water ..... 4 ounces. 

 The treatment is similar to the first-mentioned ; but as 



there is a strong bleaching tendency, it is necessary 

 that the prints be considerably over-printed. 



"The last process of gold toning to which \ve shall 

 refer, is one published during the past year (1800), as 

 being the suggestion of M. L'Abbe Laborde. We may 

 mention, however, that its advantage had been pointed 

 out some months before by Air. Hannaford, who states, 

 that a peculiarly rich purple bloom is secured, which is 

 absent when any other salt of soda is used with the 

 gold, with tlie exception of the citrate as proposed by 

 Sir. Hardwich, which has a similar effect. Mr. Hauna- 

 ford states, that it has another advantage, which the 

 Abbe confirms namely, that it may be used more 

 than once ; all other alkaline toning baths being useless 

 for toning purposes after once being used for toning. 

 The formula stands as follows : 



" Chloride of gold . . .15 grains. 

 Acetate of soda . . -7? drachms. 



Water . . . . .35 ounces. 



" The solution becomes colourless by degrees, and, at 

 the expiration of twenty-four hours, it is ready for use. 

 On removing the positive from the printing frame, it is 

 washed in two or three waters, to remove the free nitrate 

 of silver ; it is then immersed in the gold bath, where 

 it must be allowed to remain not more than twenty-five 

 to thirty seconds, when the bath is first used. 



"If the gold bath has been used before, its action is 

 slower. Experience will enable the operator to see, by the 

 successive changes in tone the proof assumes, when he 

 should remove it from the bath. If it bo removed too 

 soon, the proof assumes a disagreeable red hue after it is 

 fixed with the hypo ; on the other hand, if it be allowed 

 to remain too long in the gold bath, the proof assumes a 

 cold blue tint Between these two extremes there are a 

 variety of tones of sepia and violet, which can be secured 

 by removing the proof at the proper moment. In pro- 

 portion to the length of time tho gold bath h:us been 

 used, so we must prolong the toning until the required 

 tint appears. Tho strength of the gold bath can be 

 restored by adding fresh chloride of gold; but, before 

 making the addition, we must take care that the solution 

 is nearly colourless ; for if the chloride of gold is not in 

 combination, it will, like other chlorides, weaken the 

 proof. 



"In all cases the prints should be washed in two or 

 throe changes of water, and then immersed in the hypo- 

 sulphite of soda ; which, it is desirable, should possess 

 a strength of at least twenty per cent., or four ounces 

 to a pint of water. It is Ix'tter used fresh each time, 

 and should be neutral or slightly alkaline. Mr. Lyt 

 recommends the addition of a little Spanish white, or 

 chalk, fur that purpose. Prints on thin paper are more 

 rapidly fixed than those on thick ; but they should not, 

 in any case, be removed from the fixing bath in a shorter 

 time than ten minutes. They should then l>e washed in 

 several plentiful changes of water, within the first half- 

 hour; and subsequently soaked and washed, so as to 

 thoroughly remove all traces of hyposulphite of soda. " 



The above instructions will be of great value to all who 

 desire to produce tho best results obtainable in the 

 printing process; and, as we have already observed, our 

 own experiments affirm their useful and reliable character. 



Having thus entered fully into the entire process of 

 printing, <bc., we trust that our readers will find no 

 extraordinary difficulty in pursuing these experiments : 

 and we shall now pass on to consider a variety of photo- 

 graphic processes; which, although not employed so uni- 

 versally as those wo have minutely described still, 

 either afford interesting results, or, in an historical point 

 of view, are not to be overlooked by us. 

 Our previous pages have been an exposition of processes 

 which are universally adopted at the present time for 

 likeness and landscape taking. Our limits have, of 

 course, forbidden us to enter into every minute detail ; 

 and we must refer those of our readers who desire to 

 make a special study of the philosophy of the processes, to 

 the works of Messrs. Hunt, Hardwich, Price, and many 

 others ; in which they will find an almost exhaustion of 

 the subject. 



