GAS FROM SAP. 291 



Remarks. 



Specimen No. 2 was the colorless, translucent gum which exudes 

 freely from the wood of the root and stem of the grape vine, at any time 

 during the long period of nearly eight months, when the vital force is 

 dormant. It was entirely free from grape sugar, cane sugar, or starch. 

 When treated with water, it swelled up aud appeared to be partly solu- 

 ble and partly not. The large amount of ash contained an abundance of 

 lime. 



Specimen No. 5 was sap from a red maple which had been girdled 

 about two years previous. No. 6 was sap from a red maple, in a nor- 

 mal condition, which stood not far from No. 5. It was placed in the 

 list in order that it might be compared with No. 5. 



Specimen No. 8 was a very small quantity of sap from an apple tree. 

 When brought in, it very much resembled cider in color. It had an un- 

 pleasant, sour taste. 



Specimen No. 13 was sap from an ironwood. Though somewhat tur- 

 bid, this sap contained no solid particles which could be separated by 

 filtration. About two quarts of the sap which flowed on the day of May 

 7th, and the same amount which flowed during the following night, 

 were collected and allowed to stand in the laboratory for some months. 

 They became milky in a very short time, and fermented quite rapidly, 

 emitting a very offensive odor. There was no difference between the 

 two in this respect, so far as could be determined by their external 

 appearance. 



On the seventh of May, the sweet exudation from the hickory was 

 tested for cane sugar. By means of alcohol it was removed to a glass 

 plate, and when dry was examined under the microscope ; it was also 

 treated with Fehling's copper solution ; but neither test showed a trace 

 of cane sugar. Grape sugar was indicated to be present in abundance. 



Gas from Saj) of Acer saccharinum. 

 On the twenty-seventh of April, two and a half quarts of the first run of 

 sap from a sugar maple was collected for examination in regard to the 

 composition of the gas contained in it. By boiling, gas was obtained 

 from this sap which measured 31.2 cubic centimetres at 18° C. By intro- 

 ducing a certain amount of potassium hydrate, the volume was reduced 

 to 29.5 cubic centimetres at 18° O, owing to the absorption of carbonic 

 acid by the potassium hydrate. By inserting a certain amount of gallic 

 acid, the volume was again reduced to 22.5 cubic centimetres at 18° C, 

 due to the absorption of oxygen, thus leaving 22.5 cubic centimetres of 

 nitrogen. 



Composition by Volume. 



Gas from Sugar Maple. Atmospheric Air. 



Nitrogen 72.213 79.02 



Oxygen, 22.435 20.94 



Carbonic acid, 5.352 0.04 



100.000 100.00 



