1879.] 



On Chemical Equivalence. 



271 



the mark. To prevent evaporation during heating, the neck of the 

 flask was left long, and a narrow bent tube attached by an india- 

 rubber joint. The time was accurately noted when the flask was 

 placed in the bath. After half an hour, the flask was taken out 

 quickly, plunged into cold water, and the contents when cold trans- 

 ferred to the polarimeter tube. The tube used in the researches on 

 lactin had to be modified in these experiments, the cement not being 

 able to withstand the action of the acid. In its altered form, the 

 plate glass covers were secured by two screw rods and nuts, a thin 

 washer of gutta-percha tissue being placed between the ends of the 

 tube and the plates. This washer did not materially affect the length 

 of the column, and made the tube perfectly tight. The length of the 

 tube was thus reduced to 216 millims. 



The results of these experiments are given in the following table. 

 The quantity of acid is the only varied condition of experiment. 



Action of Hydric Chloride and Hydric Sulphate on Lactin. 



Total volume in each case 60 cub. centims. Weight of Lactin 

 = 5 grammes. 







Hydric chloride. 





Hydric sulphate. 



Half- 































hour 

 intervals. 



No. 1. 



4 cub. 

 centims. 



No. 2. 

 4 cub. 

 centims. 



No. 3. 

 7*5 cub. 

 centims. 



No. 4. 

 8 cub. 

 centims. 



No. 5. 

 4 cub. 

 centims. 



No. 6. 

 4 cub. 

 centims. 



No. 7. 

 7*5 cub. 

 centims. 





 1 



2 

 3 

 4 

 5 

 6 



9-565 

 10 -327 



10 812 



11 -218 

 11-400 

 11 -490 



9-565 



10- 197 

 10 -670 



11- 010 

 11-147 



• • 



9-565 



10 -767 



11 -383 

 11 -790 

 11 -850 



11 -852 



9-565 

 10-717 

 11 -340 

 11 -633 

 11 -742 



11 -754 



9-565 

 10-320 

 10-974 

 11 -203 

 11 -355 



9-565 



10 -278 

 10-720 



11 035 

 11 -286 



11 -445 



9 -565 



10 -843 



11 -423 

 11 -643 

 11 -850 



11 '850 



7 



8 



11 -770 



11 -670 







11 -854 



11 -607 





9 

 10 

 11 



11 '765 



11 -715 













The equation A is deduced from the average of Nos. 1 and 2 by the 

 method of least squares, the probable error of a single comparison of 

 calculated and experimental numbers being -0653. 



The equation B is similarly deduced from Nos. 5 and 6, its probable 

 error being '0587. 



C is the equation to No. '3 with a probable error '0818 

 D „ „ No. 7 „ „ „ -1063 



E „ „ No. 4 „ „ „ -0848 



