THE JOURNAL OF PHARMACOLOGY. 49 



(b) lyOgwood is decolorized by chlorinated lime, but resists the action of 

 alkalies. Wood-blue is colored red by hydrochloric acid. 



{c) Ultramarine is decolorized by hydrochloric acid with evolution of hy- 

 drogen sulphide. 



{d) Indigo (found almost solely in papers obtained from blue rags) is 

 destroyed by chlorine water and nitric acid, but resists the alkalies. 



(<f) Aniline blue is quickly decolorized by caustic soda and acquires a 

 dirty-red coloration. Chlorinated lime decolorizes it completely. Aniline 

 blue is frequently used in conjunction with Berlin blue. If such a paper 

 be treated with chlorine water, Berlin blue remains behind ; treated with 

 hydrochloric acid, the paper remains unchanged, but in the presence of 

 logwood a red coloration is produced. 



(/) Smalts occur in paper in the form of small shivers or scales that are 

 not attacked by either acids or alkalies. Thin smalt-shivers appear al- 

 most colorless under the microscope. Ultramarine and Berlin blue gran- 

 ules are much darker. The former are translucent and light-blue ; the 

 latter, especially when thick, are black and translucent at the edges only. 



Tests for the Filling of Paper. 



The filling material is put in for the purpose of filling up the spaces left 

 by the entwined fibers ; to make the paper heavier and denser, and to give 

 it a certain body. It is thereby also rendered whiter and less transparent. 

 The filling material consists usually of starch, sulphate of calcium (pearl 

 hardening), and, in coarser papers, also of powdered gypsum (annaline) 

 heavy spar (sulphate barium), and finely elutriated kaolin (benzin). 



The starches usually met with in papers are : Rice-starch in Japanese 

 papers ; wheat-starch in European silk-papers ; potato-starch (in the pro- 

 portion of 2-8 %, in letter- and other fancy papers. 



Papers sized in the mass almost invariabl}^ contain starch. 



The starch also serves the purpose of " fixing " the inorganic substances 

 used in the filling material. 



Annaline is unburnt anhydrous gypsum ; pearl-hardening is gypsum in 

 a very finely subdivided condition, obtained by the action of sulphuric 

 acid on calcium chloride. 



The above-named inorganic " filling " substances maybe recognized by 

 the various forms they exhibit under the microscope ; and the three chem- 

 ical compounds represented by gypsum, kaolin and heavy spar, may be 

 readily distinguished from each other microchemically. 



The Sizing of Paper. 

 These necessary products may also be determined by micro-chemical 

 means. Paper-size is either animal glue or a vegeto-mineral glue. At the 

 present time the latter is used almost exclusively and is composed princi- 



