doubt, be a desirable step to take if the owners of dye and print works were more in the habit of availing themselves of the service of competent chemists experienced in this branch, for then they would be able to make any extract do its full work irrespective of the state of development of the coloring matter.  Such, however, was not the case, and it was a very common thing for the consumer of dyewood extracts to require the manufacturer to prepare them specially for him so as to suit his own dyeing recipes, or in other words to give exactly the same shades, weight for weight, by his own method of dyeing as the article he was in the habit of using.  The manufacturer was thus often compelled to make many different qualities of the same extract to suit different customers.  For the same reason adulterated articles were often preferred to the pure ones.  There was, perhaps, no branch of industry in which chemical skill of a high order could be applied with greater advantage than in dyeing, and nowhere was this fact less recognized.  Some of the processes of dyeing were exceedingly wasteful and stood in much need of improvement.  He (Mr. Siebold) knew a large works in which a ton of logwood extract was used daily for black dyeing only, and he might safely assert that of this enormous quantity only a very small proportion would be fixed on the fiber, while by far the greater proportion was utterly wasted.  Such a waste could only be prevented by a searching investigation of its causes by trained skill.  Mr. Thomson had further alluded to the color obtained with logwood or logwood extract and wool mordanted with bichromate of potash, and seemed to be under the impression that the color thus obtained was not black, but blue.  This was undoubtedly the case in dyeing trials performed as tests, as these were conducted purposely with a very small proportion of coloring matter in order to admit of a better comparison of the resulting depth of shades.  But with larger proportions of logwood the color obtained was a fine bluish-black, and with the addition of a small proportion of fustic or quercitron bark to the logwood a jet black was readily produced.  With regard to Mr. Watson Smith’s observation as to fractional dyeing, he (Mr. Siebold) did not regard this method as a suitable trial for ascertaining the strength of an extract, but he admitted it was occasionally very valuable for detecting an admixture of extracts of other dyewoods, such as quercitron bark extract in logwood extract.  It was also a good method of ascertaining the speed of dyeing and hence the relative proportion of fully developed coloring matter of an extract.—­Jour.  Soc.  Chem.  Industry.

* * * * *

ORTHOCHROMATIC PHOTOGRAPHY.[1]

   [Footnote 1:  Read before the Photographic Association of
   Brooklyn.]

By OSCAR O. LITZKOW.

What I want to show is the manner in which the process has been tested.  My employer, Mr. Bierstadt, has given me permission to show you some samples, and also his chart containing the spectrum colors:  violet, indigo blue, green, yellow, orange, red, and black.  This chart has been photographed in the orthochromatic and also in the ordinary way.