DYEING AND CALICO PRINTING.

igo

addition of an excess of water. It was then simply necessary to wash the precipi-tate thoroughly, in order to render it fit for use if dissolved in alcohol or methyl-ated spirit. The chloride of lime process gives a more abundant yield than thebichromate method, but the tone of the violets obtained is redder and lesspure. We may here mention that Mr. W. H. Perkin has lately succeeded inobtaining the product of Runge’s experiment in the solid condition. He findsthat it dissolves in alcohol, forming a solution of a nearly pure blue colour,which is changed to a brownish-red by the a&ion of caustic alkali ; it there-fore differs essentially from the mauve, an alcoholic solution of which, iftreated with caustic alkali, passes from purple to violet, The blue produdt,which the author proposes to call “ Runge’s blue,” undergoes a very remark-able change when subjected to the adtion of heat. It is rapidly converted intoa purple colouring matter, which is found to be the true mauve. IndeedRunge’s blue is so prone to change into the more stable mauve that its compo-sition cannot be satisfactorily determined. Mr. Kay, in January, i860, took outa patent for producing purple-aniline,—most absurdly called “ harmaline,”—by adding to sulphate of aniline peroxide of manganese, and heating thismixture to ioo°, when the “ harmaline ” so produced remained in solution,and was separated from an insoluble deposit. The dissolved colour was pre-cipitated by adding to the solution ammonia in sufficient quantity to neutralisethe acid, after which the insoluble colour was washed, dried, and dissolved inmethylated alcohol. In January, i860, Mr. Greville Williams patented the useof permanganate of potassa as a means of oxidising aniline and producingpurples and other colours; at about the same time Mr.JD. Price took out apatent for adting on sulphate of aniline by means of the peroxide of lead.In i860 Dale and Caro patented the use of chloride of copper, in the propor-tion of 6 equivalents to 1 of a neutral salt of aniline. In place of chloride ofcopper, a mixture of sulphate of copper and common salt may be used inequivalent proportions. The quantity of water necessary to dissolve themixture is added, and the whole is then boiled till a precipitate appears, whichcontains the colouring matter. At the expiration of three or four hours theprocess is completed. The precipitate is colledted on a filter, and washedwith a solution of soda or carbonate of soda so long as the washings containchlorides. The residue is then extracted with boiling water so long as any-thing dissolves. The solutions thus obtained are filtered, and precipitatedwith a small quantity of soda or carbonate of soda. The colour thusobtained is ready for use. The matter insoluble in boiling water still containsa violet, which may be extracted by treatment with boiling dilute alcohol in adisplacement apparatus.

On the 12th of January, 1861, another interesting process to obtain anilinepurple was patented by M. A. Girard : pure aniline red (known as magenta)is mixed with an equal weight of aniline, and the mixture heated for severalhours to 329° F., when the mass is changed to a fine purple colour, requiringonly to be mixed with water and hydrochloric acid to remove any aniline orred dye in excess, leaving the purple insoluble; but on being well washedwith water this becomes soluble in alcohol, acetic acid, wood naphtha, and boilingwater, slightly acidulated with acetic acid. The French call this VioletImperial.

In 1862 Mr. G. C. Nicholson secured a patent for producing a very beautiful