Journal of 



Applied Microscopy 



and 



Laboratory Methods. 



VOLUME IV. AUGUST, 1901. NUMBER 8 



Table of Specific Gravities of Saturated Solutions and 

 Solubilities of Anilin Stains. 



In the following tables will be found in the first two columns the specific 

 gravity of saturated solutions of the various anilin stains, made in the cold and 

 by boiling. Those made in the cold were allowed to stand with an excess of 

 the stain, the bottle being vigorously shaken daily, for two weeks. 



The solutions made with hot water were kept at the boiling point for twenty 

 minutes and well stirred. Both solutions were carefully filtered and the s. g. 

 ascertained by means of the specific gravity bottle. Correction was made for 

 temperature and the average of five weighings was taken in each case. 



The third column contains the increase in weight of 95 per cent, alcohol 

 when various stains are dissolved in it to saturation. The s. g. in this case may 

 be obtained by adding the weight of the alcohol in use to the figures given in 

 the table. The s. g. of the solution is not given for the reason that the various 

 samples of alcohol obtained commercially as 95 per cent, vary considerably in 

 actual percentage and hence in weight. The solvent power varies practically 

 not at all, so that by adding the weight of the sample at hand to the figures in 

 the table the s. g. may be obtained sufficiently accurate for most working 

 purposes. 



The various formulae which one encounters constantly call for saturated 

 solutions of the various stains, and it is usually the custom to add three or four 

 times as much of the dry stain as is really necessary. This can be obviated by 

 a glance at the table. While it is true that all solutions will change slightly in 

 volume when they have substances dissolved in them to the point of saturation, 

 still the change is usually small, and we may also take the table as a guide to 

 the solubilities of the stains in making them up, thereby avoiding waste. 



In the first column the approximate solubilities in grams per hundred c.c. of 

 water may be obtained by simply subtracting 100 from the s. g. 



In the last column the increase in weight is given and may be taken directly 

 as the approximate solubility. 



A slight error will be found in several of the stains, which seems to be caused 

 by a chemical change when the stains are boiled. This is notably the case with 



(1397) 



