Aug. 25. 1855.] 



NOTES AND QUERIES. 



151 



embrace the whole theory of the alteration of positive 

 prints. 



He considered that the first point to be attended to is the 

 modifications which the chloride of silver, which is formed 

 on the surface of the paper, undergoes in the different baths. 

 In fact, if we once knew exactly what substance we had to 

 deal with, it would be easier to find out the causes which 

 alter that substance, and so occasion the destruction of 

 the prints. If we consider the paper at the moment when 

 it is placed in the pressure-frame (we are speaking, of 

 course, of paper prepared with chloride of silver), it 

 darkens under the influence of light ; and if, after a pre- 

 liminar}' washing to take away the excess of nitrate of 

 silver, it is passed througli fresh liyposulphite of soda, 

 the chloride of silver is dissolved, and there remains on 

 the surface a reddish substance Avhich forms the picture. 



After divers reactions it seems that this substance is 

 silver in a finely-divided state, and no longer united to 

 the chlorine, although analysis always gives a certain 

 quantity of chlorine which cannot be removed by the 

 fixing and washing. As this same quantity of chlorine 

 has been found in paper not prepared, as well as in that 

 prepared with chloride of silver and fixed by hyposulphite 

 of soda before exposure to the light, it would seem that it 

 combines with tlie organic matter of the paper at the 

 time of the bleaching of the pulp. 



He stated that he should hereafter explain on what 

 experiments he had founded the idea that the image fixed 

 by a bath of fresh hyposulphite is formed by the silver 

 alone, and does not still retain the chloride or the sub- 

 chloride of silver. 



It was necessary to detennine whether, when the print 

 is properly washed, it retains any hyposulphite of soda, 

 or sulphur combined in any other manner. This ana- 

 lysis, often repeated, always gave a negative result ; the 

 print fixed in fresh and /)ure hyposulphite of soda properly 

 washed shows no trace of sulphur. It maj' be concluded, 

 then, that hyposulphite of soda properly employed has 

 not the injurious properties that have been attributed to 

 it ; it is not that which is the cause of the deterioration 

 of the prints : and this accords with experience, for 

 amongst the prints fixed by hyposulphite of soda, there 

 are some ver}'' well preserved until now ; others, on the 

 contrary, have faded rapidly, and it cannot be supposed 

 that the same agent employed in the same manner pre- 

 serves some and deteriorates others. It is not then fresh 

 hyposnlphite of soda that deteriorates the prints. Con- 

 tinuing the series of experiments, the red prints have 

 been changed to a black tone by plunging them in old 

 hyposulphite. These prints, properly washed and ana- 

 lysed, show a very perceptible quantity of sulphur. The 

 silver has become black because it has combined with 

 sulphur. Old hyposulphite of soda, or at least the mix- 

 ture which is usually called so, has then an action quite 

 different to the fresh hyposulphite. It owes these new pro- 

 perties to a substance which is produced by the action of 

 acids or different metallic salts on the hyposulphite of 

 soda ; and this may be proved by the following experi- 

 ments : Take pure hj'posulphite of soda not having been 

 used before, employ it to fix a print; add chloride of 

 silver to this hyposulphite, and fix immediately a second 

 print, it will preserve sensibly the same red tint as the 

 first ; the fresh hyposulphite and the hyposulphite 

 charged with chloride of silver have then the same ac- 

 tion. But at the end of some time, when the reaction of 

 the chloride of silver on the hyposulphite of soda is ac- 

 complished, a deposit of black sulphide of silver will be 

 observed on the sides of the vessel. If you fix a third 

 print, you can make it take all the variety of tones that 

 the old hyposulphites give. It is not, then, only to the 

 presence of metallic salts that the old hyposulphite of 

 No. 304.] 



soda owes its colouring properties, but to a new substance 

 that the metallic salts have given birth to. It is this new 

 composition (probably tetrathionate of soda, Na O, S4 O5) 

 which sulphurises the prints ; and it appears that the cause 

 of their deterioration is that sulphuration, whether it is 

 in the old hyposulphites of soda, or in the new hyposul- 

 phites mixed with acids, which disengage sulphur and hy- 

 drosulphuric acid. In fact these sulphurised prints, left in 

 water in contact with the air for a verj' short time, become 

 rapidly yellow, and finish by disappearing, whilst the print 

 not changed, placed in the same conditions, does not stir. 

 If the print is only partially plunged in water, or if there 

 are bubbles of air interposed, it may be remarked that 

 the alteration goes on with extreme rapidity at that part 

 of the paper which has been at the same time in contact 

 with the air and the water. The prints then deteriorate 

 much quicker when they are most exposed to moisture, 

 and perhaps would keep very well in a perfectly dry air. 

 This is a very simple explanation of this fact, that certain 

 prints fade rapidly when they are pasted, whilst others, 

 prepared by the same process, keep very well in portfolios. 

 Sometimes the same print will only fade in the parts 

 pasted ; it is because the paste attracts the dampness of 

 the air, and the print becomes in the conditions above 

 described. 



The conditions under which this deterioration takes 

 place indicate evidently the oxidising action of the air ; 

 nevertheless we cannot be certain that there is a change 

 from sulphide of silver to sulphate. The sulphate of 

 silver, in fact, becomes black bj' the action of alkaline 

 sulphides, whilst the faded prints, instead of becoming 

 black in a sulphurous solution, fade more and more. 



MINI. Davanne and Girard regretted that they had not 

 yet fully investigated the subject, but they proposed to 

 continue their experiments, and hoped soon to present to 

 the Society the complete theory of the preservation of 

 positive photographs. 



Hit^lisi to Minax <%\itxit&. 



The Burning of Jesuitical Books (Yol. x., 

 p. 406.). — Mr. Cramp speaks of "the interest 

 Bifrons, in liis real character (i. e. of Junius), felt 

 in the fate of the Jesuits," &c. How can this be 

 reconciled with the fact, that the letter of Bifrons 

 was published nine months before the first of the 

 Letters of Junius ? 



Mr. Cramp's last paragraph shows, that he has 

 overlooked the note on p. 185. of the Junius Dis- 

 covered; in which the origin, in 1766, of " Junius's 

 unappeasable wrath" against the Duke of Grafton 

 is pointed out. 



The non-receipt, until last week, ofVol. x. of 

 " N. & Q." will account for the lateness of this 

 notice of Mr. Cramp's communication. Eric. 



Ville-Marie, Canada. 



Armorial Bearings of the Clere Family (Vol. xii., 

 p, 84.). — The following particulars may perhaps 

 assist Mr. Taylor in his investigations concern- 

 ing the Clere family. 



The arms of Spencer of Nettlested, co. Suf- 

 folk, were, — Quarterly. First, Argent, on a bend 

 sable, three mullets of the first ; second, Gules, a 

 fret or. 



