19 



SOLUBILITY WITH SEVERAL REAGENTS. 



It is important in studying the properties of the stalks to determine 

 their solubility in different reagents. Since dilute acids and alkalies 

 are the common hydrolyzing agents, the first determination was that of 

 the percentage of material dissolved by these bodies. The process 

 was conducted as follows: 



Ten grams of the material were digested half an hour at three 

 atmospheres with 200 cc. of 1.25 per cent sulphuric acid. After cool- 

 ing the mass was thrown on a filte'r and washed with water until the 

 acid reaction disappeared. The residue was dried and weighed. The 

 percentages given below are on the material free of water : 



Solubility of different portions in acid. 



It will be seen by the above figures that this reagent reacts most 

 vigorously on the pith and least vigorously on the shells, the nodes 

 occupying an intermediate position. 



DIGESTION WITH ALKALI. 



The digestion with alkali was carried on at ordinary pressures and 

 in the autoclave at a pressure of three atmospheres. The time of diges- 

 tion in each case was half an hour. In each instance 10 grams of the 

 different materials were digested with 200 cc of a 1 per cent caustic 

 soda solution. The residue on cooling was washed thoroughly with 

 water, then with dilute acetic acid, and again with water, dried, and 

 weighed. The solubility of the different materials in this reagent 

 under the two conditions named was as follows: 



Solubility of different portions in alkali. 



The action of caustic alkali at atmospheric pressure and at a boiling 

 temperature is less efficient than heating under pressure. The latter 

 process dissolves about half of the material and the former about 44 

 per cent. 



