1607] Wheeler — Color Test for Lignocelluloses. 
25 
ing for some hours the red color develops. Since the best 
results are obtained when free acid is present, various 
strengths of hydrochloric acid were tried from one-half to a 
twelve per cent, solution but no important difference could 
be observed. It is convenient to use an acid of specific grav- 
ity 1.06. A study of various concentrations of the parani- 
traniline in acid solution revealed no differences of conse- 
quence. It was observed that in all cases hot solutions pro- 
duced much quicker results than cold ones. In fact hot solu- 
tions seemed to give the full depth of color instantaneously. 
The reagent was applied to a wide variet}^ of woods, to 
jute, to oat straw and to many samples of paper. A No. 1 
book paper showed numerous small red fibres, indicating 
adulteration with mechanical wood or else incomplete con- 
version of the lignocellulose. A yellow paper containing 
five per cent, of mechanical wood gave a deeper color, like- 
wise a salmon pink paper. A very deep blue paper made of 
sulphite cellulose showed scattering red fibres which were 
easily seen. A sample of white paper made from bleached 
sulphite gave no trace of color. 
i A striking lecture experiment is carried out by projecting 
a quantity of the hot solution against a large sheet of paper 
made of mechanical wood, such as newspaper stock. 
In conclusion, the reagent is made by dissolving two grams 
I of paranitraniline in one hundred cubic centimeters of hydro- 
| chloric acid, either of specific gravity 1.06 or a 4N solution. 
1 When used hot, a blood red color is instantaneously 
obtained with lignocelluloses. 
University of North Carolina, 
February 21 , 1907. 
