CHEMISTKY. 



155 



vent for the greater part of the aniline dyes has 

 been discovered by M. G. de Claubry, and com- 

 municated by him in a 'paper (March 27, 1865, 

 it appears) to the French Academy of Sciences. 

 In place of alcohol and methylated spirit, which 

 are high-priced or injurious to the workmen, 

 M. de Claubry proposes to substitute a decoc- 

 tion of Panama bark (Quillaria saponaria) or 

 of Egyptian soap- wort (Gypsophila strutium). 

 Solutions of the coloring products are readily 

 obtained by pouring the boiling decoction upon 

 the powder, repeating the operation after stir- 

 ring and decanting, if part of the powder re- 

 main undissolved. The red dyes thus dissolve 

 most readily ; the blues, less so. For a purple 

 dye, accordingly, it may be necessary to mix 

 the solutions at the last, in order to obtain the 

 required hue. It is stated, also, that the new 

 menstruum insures greater uniformity of tone, 

 since it is not, like the alcoholic solutions, liable 

 to change of constitution by evaporation during 

 use. 



Processes for Reviving the Writing of Old 

 Documents, on Parchment or Paper. The 

 process recommended for the purpose named 

 (more especially for parchments, it appears), by 

 M. E. Moride, and given in Le Technologiste for 

 August, 1864, is as follows: 



1. Moisten the parchment as speedily as pos- 

 sible, and without agitation or rumpling, in cold 

 distilled water. 2. Having let the sheet drip, 

 plunge it during five seconds only in a solution 

 of oxalic acid, strength of one-fifth. 3. "Wash 

 rapidly in two waters ; any oxalate of lime 

 with which, as is often the case, the parchment 

 may be covered, will thus be removed. 4. Intro- 

 duce the manuscript into a solution of 10 gram- 

 mes of gallic acid in 300 grammes of distilled 

 water. 5. After the reappearance of the charac- 

 ters, wash the parchment in a plenty of water, 

 and dry it between sheets of bibulous paper, 

 renewed as long as required ; and finally, sub- 

 mit it to the action of a press. To restore sim- 

 ply a few words or lines that may be well-nigh 

 effaced, apply the liquids with a camel's-hair 

 pencil, following regularly the order above 

 given, and using at the close alternately, first, 

 the acid solution and bibulous paper, and then 

 water and other paper of like sort to absorb it. 

 Very" great delicacy and promptitude' are re- 

 quisite throughout the operation ; and, since in 

 spite of precautions the writing will sometimes 

 spread into cloudy spots, and remain illegible, 

 this risk should be borne in mind ; and though 

 the rightful holders of writings may resort to 

 the process given, it would scarcely be proper 

 for the legal depositaries of documents held in 

 trust for others, to incur its hazards. 



In the journal quoted, also, date of Decem- 

 ber, 1864, M. E. Knecht-Senefelder considers 

 generally the causes in the composition of 

 various sorts of paper and of factitious parch- 

 ment, and in the varying composition and qual- 

 ities of inks, &c. of the gradual alteration or 

 in many cases effacement, with lapse of time, 

 of the writing of deeds and other documents ; 



and finding, in case of common inks, the prin- 

 cipal cause of such changes in the differing pro- 

 portions of the sulphate of iron and gallic acid 

 (of which such inks are essentially composed), 

 employed in their preparation, and the con- 

 sequent different degrees of facility with which 

 the paper takes up and retains these ingredients 

 respectively ; or else, in an absorbent action ex- 

 ercised by calcareous substances present in the 

 paper, he proposes accordingly the following 

 mode of proceeding for the restoration general- 

 ly of old writings on parchment or on paper of 

 any sort : 



Into one of two vials put 1 part gallic acid 

 and 200 parts distilled water; into the other 

 put 1 part sulphate of iron and 200 parts dis- 

 tilled water. Begin by making trial of the solu- 

 tions by means of a small camel's-hair pencil, 

 applying one of them live or six times upon 

 some single letter of the document, and the 

 other in like manner with another pencil upon 

 some other letter near to the former. Observe 

 which of the two applications renders its letter the 

 more black ; and then employ that solution which 

 hds succeeded best, for bathing the entire sheet. 

 Or pass the proper solution lightly with a pen- 

 cil two or three times over the lines of writing. 

 Finally, it is well to turn pure water over the 

 sheet before letting it dry, in order to prevent 

 a yellow discoloration of it due to the materials 

 applied ; though it is also stated that such tint 

 can subsequently be removed, if necessary, by a 

 weak solution of bichloride of tin, in the pro- 

 portions given for the solutions last named 

 above. 



Chemistry in the Smithsonian Institution. 

 In the Report of this Institution for 1864, the 

 Secretary states that, " In compliance with re- 

 quests made by different departments of the 

 Government and of Congress, particularly since 

 the war, it [the Institution] has conducted 

 various series of investigations, principally in 

 relation to questions involving mechanical, 

 chemical, or physical principles, and has made 

 reports on subjects of this kind amounting, in 

 the aggregate, to several hundred." In order 

 to facilitate such researches, a laboratory has 

 been established and kept constantly in work- 

 ing condition ; and the privilege of using it has 

 been given to various competent persons, for 

 experimenting in the different branches of phys- 

 ical science. The laboratory, at the time of 

 publication, was occupied by Dr. Wetherill, who 

 was conducting analyses of air from the halls 

 of Congress, &c. ; and from these a report was 

 to be made, under direction of the Institution, 

 on the ventilation of public buildings of the 

 city of Washington. As among important pub- 

 lications, more or less directly connected with 

 the subject of chemistry, which have been is- 

 sued by tLe Institution, are named, the work 

 of Dr. Hare, on the Explosibility of Nitre; 

 that of Drs. Gibbs and Genth, on the Ammonia- 

 Cobalt Bases ; and that of Dr. H. Draper, on 

 Astronomical Photography. Many of the Re- 

 ports, also, since 1853, have contained reviews 



