-------------------------+--------+-------+ Strength of Solution. | [eta] | Z. | -------------------------+--------+-------| C. 80 per cent. Ghatti. |0.3642 | 2,937 | D. 75 per cent. Ghatti. |0.33095 | 2,669 | E. 77.5 per cent. Ghatti.|0.4860 | 3,819 | -------------------------+--------+-------+ This last solution E we called for convenience the "maximum viscosity" solution, as we believe it to be a 10 per cent. solution containing arabin very nearly saturated with metarabin. As will be observed, its viscosity differs widely from those of solutions C and D, between which it lies in percentage of Ghatti. The first named solution C contains _too little_ of gum arabic to dissolve the whole of the metarabin. Consequently there is a residue left undissolved, which of course diminishes its viscosity. The second solution D is too low in viscosity, as it still contains too much of the weak gum arabic, and as will be seen further on, a very slight change in the proportions increases or decreases the viscosity enormously. We next tried a series of similar experiments with a Ghatti containing far less insoluble residue and which consequently would require less gum arabic to produce a perfect solution. Mixtures were made in the following proportions, viz.: ----------------------+------------+-----------+ ----- | 13.3 per Cent. Ghatti. | ----------------------+------------+-----------+ F. Pressure 200 mm. | [eta] | Z. | Temperature 15° C. | 0.0976 | 787 | ----------------------+------------+-----------+ ----------------------+------------+-----------+ ----- | 86.6 per Cent. Ghatti. | ----------------------+------------+-----------+ G. Pressure 200 mm. | [eta] | Z. | Temperature 15° C. | 0.4336 | 3,497 | ----------------------+------------+-----------+ This latter solution is approaching fairly closely to our "maximum viscosity" with the previous Ghatti, and probably a very slight decrease in the amount of gum arabic would bring about the required increase in viscosity.