May 14. 1853.] 



NOTES AND QUERIES. 



485 



such immersion, again to wash well in water. I 

 shall feel greatly obliged if Dr. D. will be kind 

 enough to state whether the first-named washing 

 is requisite, or whether the properties of the hypo., 

 or the beauty of the picture, will be in any way 

 injured by the previous solutions not having been 

 washed oif, prior to the fixing. C. W. 



[We have submitted this Query to Dr. Diamond, 

 who informs us that he never adopts the practice of 

 washing off the developing fluid, and considers it not 

 only needless, but sometimes prejudicial, as when such 

 washing has not been resorted to, the hyposulphite so- 

 lution flows more readily over the picture, and causes 

 none of the unpleasant stains which frequently occur in 

 pictures which have been previously washed, especially 

 if hard water has been used. But besides this, and the 

 saving of time, the doing away with this unnecessary 

 washing economises water, which in out-door practice 

 is often a great consideration. Dr. Diamond would 

 again impress upon our readers the advantage of using 

 the hyposulpliite over and over again, merely keeping 

 tip its full strength by the addition of fresh crystals of 

 the salt from time to time, as such practice produces 

 pictures of whiter and softer tone than are ever pro- 

 duced by the raw solution.] 



Colouring Collodion Pictures (Vol. vii., p. 388.) 

 — A patent has just been taken out (dated Sep- 

 tember 23, 1852) for this purpose, by Mons. J. L. 

 Tardieu, of Paris. He terms his process tardio- 

 chromy. It consists in applying oil or other colours 

 at the back of the pictures, so as to give the re- 

 quisite tints to the several parts of the photograph, 

 without at all interfering with its extreme delicacy. 

 It may even, in some cases, be used to remedy de- 

 fects in the photographic picture. The claim is 

 essentially for the application of colours at the 

 back, instead of on the surface of photographs, 

 •whatever kind of colours may be used. It is 

 therefore, of course, applicable only to photographs 

 taken on paper, glass, or some transparent material. 



A. C. Wilson. 



Wanted^ a simple Test for a good Lens. — As all 

 writers on Photography agree that the first great 

 essential for successful practice is a good lens — that 

 is to say, a lens of which the visual and chemical 

 foci coincide — can any of the scientific readers of 

 " N. & Q." point out any simple test by which un- 

 scientific parties desirous of practising photography 

 may be enabled to judge of the goodness of a lens? 

 A country gentleman, like myself, may purchase a 

 lens from an eminent house, with an assurance that 

 it is everything that can be desired (and I am not 

 putting an imaginary case), and may succeed in 

 getting beautiful images upon his focussing-glass, 

 but very unsatisfactory pictures ; and it may not 

 be until he has almost abandoned photography, in 

 despair at his own want of skill, that he has the 

 opportunity of showing his apparatus, manipulation, 

 &c. to some more practised hand, who is enabled 



to prove that the lens was not capable of doing what 

 the vendors stated it could do. Surely scientific 

 men must know of a simple test which would save 

 the disappointment I have described ; and I hope 

 some one will take pity upon me, and send it to 

 "N. & Q.," for the benefit of myself and every 

 other Country Practitioner. 



Photographic Tent — Restoration of Faded Nega- 

 tives.— In Vol. vii., p. 462., I find M. F. M. in- 

 quiring for a cheap and portable tent, effective for 

 photographic operations out of doors. I have for 

 the last two years, and in mid-day (June), pre- 

 pared calotype paper, and also the collodion glass 

 plates, for the camera, under a tent of glazed yel- 

 low calico of only a single thickness : the light 

 admitted is very great, but does not in the least 

 injure the most sensitive plate or paper. It is 

 made square like a large bag, so that in a room I 

 can use it double as a blind ; and out of doors, in 

 a high wind, I have crept into it, and prepared my 

 paper opposite the object I intended to calotype. 



I .should be glad if any of your readers would 

 inform me how a faded negative calotype can be 

 restored to its original strength. I last year took 

 a great number, some of which have nearly faded 

 away ; and others are as strong, and as able to be 

 used to print from, as when first done. The paper 

 was prepared with the single iodide of silver solu- 

 tion, and rendered sensitive with aceto-nitrate sil. 

 and gallic acid in the usual way. I attribute the 

 fading to the hyposulphate not being got rid of; 

 and the question is. Can the picture be restored ? 



Are Db. Diamond's Notes published yet ? 



S. S. B., Jun. 



^t^filizi to Miwax (jaucrfcS. 



Gibbons Library (Vol. vii., p. 407.).— I visited 

 it in 1825, in company with Dr. Scholl, of Lau- 

 sanne, who took charge of it for Mr. Beckford. It 

 was sold between 1830 and 1835, partly by auction, 

 partly by, private sale in detail. 



James Dennistoun. 



Robert Drury (Vol. v., p. 533.). — I am afraid 

 that the credit attachable to Drury's Madagascar 

 is not supported or strengthened by the announce- 

 ment that the author was " every day to be spoken 

 with" at Old Tom's Coflee House inBirchin Lane. 

 The Apparition of Mrs. Veal, and other produc- 

 tions of a similar description, should make us very 

 doubtful as regards the literature of the earlier 

 part of the eighteenth century. Might not a per- 

 son have been suborned to represent the fictitious 

 Robert Drury, to the benefit of the coffee-house 

 keeper as well as the publisher ? I am induced to 

 express this suspicion by a parallel case of the 

 same period. The Ten Years' Voyages of Captain 

 George Roberts, London, 1726, is universally, I 



