May 12. 1855.] 



NOTES AND QUERIES. 



371 



equations cubiques, pares et aftect^s. L'Isagoge de I'Al- 

 gebre. La Methodede mettre en Perspectiue toutes sortes 

 d'objects par le moyen du Compas de proportion. La 

 Theorie des Planetes, distingu^e selon les hypotheses de 

 la terre immobile et mobile. L'Introduction en la Chro- 

 nologic, auec une Table des choses plus notables par ordre 

 alphabetique : Et ua Catalogue des meilleurs Autheurs 

 des Mathematiques.' 



Both headings appear on the same title-page. 

 The historical part commences at, p. 200. with a 

 " Distinction de la suite du temps par les choses les 

 plus notables en Chronologie, et descriuant plus 

 particulierement les principaux autheurs qui ont 

 inuente ou escrit quelque chose des Mathema- 

 tiques." At page 245. there follows a " Table par 

 ordre alphabetique des choses notables par les- 

 quels nous auons distingue la suite du temps ;" at 

 p. 252. we have a " Table par ordre alphabetique 

 des Autheurs Mathematiques contenus en la 

 Chronologie precedente;" and, lastly, at p. 255. a 

 " Catalogue des principaux Autheurs qui ont 

 escrit des Mathematiques." In the last catalogue 

 the authors are arranged under their respective 

 subjects. This system of reference is admirable, 

 and, if imitated, would greatly enhance the value 

 of similar narratives where it is infinitely more 

 needed than in the 62 pages which comprise 

 Herigone's historical labours. The words " Acheue 

 d'imprimer le 2 luillet 1642" appear at the end 

 of the volume. James CocKtE, M.A., 



F.K.A.S., F.C.P.S., &c. 

 4. Pump Court, Temple. 



PHOTOGKAPHIC CORRESPONDENCE. 



How to deepen a Positive Collodion Picture into a good 

 printing Negative. — Having frequently been asked the 

 above question, will you allow me 'to reply through 

 " N. & Q ," that I use the following mode with general 

 success. I put two drachms of bichloride of mercury into 

 a stbppered bottle, with the same weight of chloride of 

 ammonia, and add ten ounces of water. It soon dissolves, 

 and may be kept any length of time for use. Then, after 

 a picture is thoroughly washed from the hypo-sulph. of 

 soda, I pour some of 'this fluid rapidly over the whole 

 surface, beginning at one corner, so that it may flow 

 evenly and without any hesitation -oif at the opposite 

 diagonal corner; and immediately wash it perfectly with 

 water. If allowed to remain, a white picture will be the 

 result ; which must be afterwards blackened with weak 

 hypo, as recommended by Mr. Archer : but it is far more 

 convenient to use the solution I have described, as it acts 

 most perfectly, and there is little danger of its destroying 

 the collodion film, which is often done when more power- 

 ful agents are used. The half-tones are in no measure 

 injured by this process. Paper negatives acquire inten- 

 sity by very quick manipulation in the same way. 



Hugh W. Diamond. 



3Ir. Sisson on Acetate and Nitrate of Lead. — La 

 Lumiere of April 7 publishes the following extract from 

 & letter addressed to the editor by Me. J. Lawson Sisson, 

 upon the employment of acetate and nitrate of lead in 

 photography. Mu. Sisson remarks, " that in his recent 



communication to Im, Lumiere, M. Julien Blot mentions 

 M. Laborde as being the first who employed nitrate and 

 acetate of lead in photography. In 1851 M. Mailer (of 

 Patna, in th* East Indies) made nse of a solution of 

 nitrate of lead to wash the negative paper before iodizing 

 it. The iodide of lead being completely soluble in the 

 solution of nitrate of silver, he thought that it would 

 furnish a very useful photographic agent. His process 

 was published in The Athenceum, with a note in which 

 the author said that this process appeared to him ap- 

 plicable to albumen and collodion. Having made some 

 experiments with nitrate of lead, I have found that it 

 gives excellent results in the preparation of protonitrate 

 of iron for collodion positives. It will keep an indefinite 

 time (this is a very remarkable fact), and never injures 

 the picture if it is poured on it with care ; it produces 

 also very brilliant tones, if the manipulations are pro- 

 perly done. The formula which I employ is this : 



Protosulphate of iron - - - - 6 grammes. 



Common water ----- - 248 



When it is dissolved, add nitrate of lead 3-90. 



Stir it well, till the decomposition is complete; let it 

 settle ; decant or filter it ; then add to the clear liquid : 



Acetic acid - - - - - - 12 grammes. 



Or bromic acid ----- ditto. 



Lawson Sisson. 



New Process for biting in, in heliographic Engraving; 

 communicated by M. Ni€pce de Saint- Victor to " La Lu- 

 miere." — " Since the publication of my last memoir, I have 

 been engaged in investigations having for their object 

 the replacing the aqua fortis used in heliographic en- 

 graving on steel. 



" The fumigations that I mentioned are certainly a 

 great assistance, but their employment is difficult. They 

 often give too much or too little resistance to the varnish, 

 so that it has become necessary to seek for another mor- 

 dant than aqua fortis, which will act upon the metal 

 without attacking the varnish. Amongst a great num- 

 ber of experiments that I have made on this subject, I 

 have found nothing better than water saturated with 

 iodine, at a temperature of 10 to 15 C, or more (50° to 

 59° Fahrenheit) ; so that it has a golden-yellow colour, 

 not passing to orange-red. 



" The biting in is commenced by coverjng the plate 

 with the iodized water; then, after ten minutes or a 

 quarter of an hour, the iodized water is renewed, for the 

 tirst water will no longer contain any iodine : a part will 

 have combined with the steel, forming iodide of iron, and 

 the rest will have volatilized ; so that it is important to 

 change the iodized water two or three times, that is to 

 say, until the plate appears to be sufficiently bitten in. 



" The biting in proceeds slowly, and it will never be 

 sufficiently deep unless we finish hj using water slightly 

 acidulated with nitric acid. It then acts siiificiently to 

 bite in the metal deeper than the iodine, without attack- 

 ing the varnish. The application of this process has given 

 M. Riflfaut, engraver, excellent results. 



" NiEPCE DE Saint- Victor." 



Sutton's " Calotype Process." — There should now be no 

 lack of good photographers, for many and excellent are the 

 treatises upon the art which have from time to time been 

 published. To those already issued may now be added, 

 one very clear and minute in its details, and which will 

 be found to contain many hints which even practised 

 hands will be the better for. The work to which we refer 

 is entitled. The Calotype Process, a Handbook to Photo- 

 graphy on Paper, by Thomas Sutton, B.A., Caius College, 

 Cambridge ; and those who, with the old proverb, prefer 



