180 Mr. S. B. Schryver. Investigations dealing with the 



introduced into Erlenmeyer flasks containing salt solutions of varying 

 strength, and the erosion was measured after 16 hours. The results are 

 given in Table III. 



Table III. 





5N/10. 



4N/10. 



3N/10. 



2N/10. 



IN/10. 



LiCl 



50 









15 



NaCl 



50 



50 



47 



28 



12 



KCl 



50 



50 



48 



28 



12 



MgCl, 



50 







50 



46 



35 



14 



It was found, however, that the addition of calcium salt to the above salt 

 solutions could inhibit their erosive action, and these experiments, described 

 below, offer a striking illustration of the " antagonistic " action of salts. 



The same gel in " Mett " tubes was introduced into 20 c.c. of N salt 

 solutions, diluted with an equal volume of calcium chloride solutions of 

 varying strength. One length of 25 mm. was used in each experiment, and 

 the result was measured after 16 hours. The results are given in Table IV. 



Table IV. 



Solution. 



Erosion. 



20 c.c. N NaCl + 20 c.c. N/32 CaCL 



25 



+ 20 c.c. N/16 CaCl 2 



' 



20 c.c. N KC1 + 20 c.c. N/32 CaCL 



25 



„ „ +20 c.c. N/16 CaCL 







20c.c.NMgCL + 20 c.c. N/32 CaCL 



25 



+ 20 c.c. N/16 CaCl 2 



8 



„ +20 c.c. N/8 CaCL 







In water alone the erosion was 13 mm. after 16 hours, and this was 

 almost entirely stopped by the addition of calcium chloride to the amount 

 of N/64. 



It will be seen from the above experiments that the gel is entirely 

 destroyed by solutions of the chlorides of sodium, potassium and magnesium 

 of the concentration N/2. This destructive action is, however, antagonised 

 completely by the presence of calcium chloride in the strength of N/32 in the 

 case of the two first-mentioned salts and in the strength of N/16 in the case 

 of the third ; there is, however, but little erosion in the presence of 

 magnesium chloride even when the strength of the calcium chloride is only 

 N/32. 



Calcium chloxide can also protect the gel against the erosive action of 



