84 



MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



states the composition of crystallized proteid from squash seed as given below, where the various 

 analyses of vegetable globulin, except this earlier one of Griibler, are tabulated. 



I have lately obtained from flaxseed a crystallized globulin whose composition agrees quite 

 nearly with that of squash seed vitellin. 



Composition of regetable globulin. 



XII. — Methods of Analysis. 



Drying. — Preparations preceding 12 were dried in hydrogen at 110'^ C. to a constant weight. 

 Those following were dried in air at 110° C. 



Carbon and hydrogen. — Carbon and hydrogen were determined by combustion in a platinum 

 boat in open tube filled with copper oxide and containing in addition a layer of lead chromate 

 and a roll of metallic copper. In the .analyses preceding that of preparation 12 the portions taken 

 for each carbon determination were dried separately to a constant weight at 110° C. in a stream 

 of hydrogen, and weighed in a closed tube. For those following, the entire sample was dried to a 

 constant weight in air. By the latter method of drying,, slightly higher percentages of hydrogen 

 were obtained when the substance analyzed was in the form of a light hygroscopic powder; 

 the dense preparations obtained from alkaline solutions, not being so hygroscopic, gave slightly 

 lower percentages of hydrogen. The difference is attributable to moist ure unavoidably absoi-bed 

 by the dry, light powder during weighing and transferring to the combustion-tube, the analyses 

 being made in very damp summer weather. 



The accuracy of the determinations was rei)eatedly controlled by analyses made on j^ure 

 sugar. 



Nitrogen. — Nitrogen determinations were made by both the Kjeldahl and Dumas methods, in 

 the manner customarily followed in the laboratory of this station.* Preceding 12 the determina- 

 tions were made upon the substance dried over sulphuric acid, a correction being applied for the 

 moisture contained in the sample as found by drying it at 110° C. Subsequent determinations 

 were made on the fully-dried sample. 



Sulplmr. — Sulphur was determined by fusion Avitli sodium hydroxide and potassium nitrate, 

 dissolving the fused mass in water, neuti'alizing the alkali with a considerable excess of hydro- 

 chloric acid, evaporating to dryness to decompose nitrates and to remove excess of acid, dissolv- 

 ing the dry residue in 600 or 700 centimeters of water, allowing the solution to stand for twenty- 

 four hours, filtering, heating to boiling, and precipitating with 3 cc. of a 10 per cent solution of 

 barium chloride. 



In the analyses of 8, evaporation to dryness was omitted, the barium sulphate being fiised 

 with sodium carbonate and reprecipitated. In all cases the ash of the preparations was carefully 

 examined for sulphates, but none was found in any instance. 



Blank experiments with the reagents proved them to be entirely free from sulphur. 



Ash. — Ash was determined by combustion in a platinum crucible, no difficulty being experi- 

 enced in burning any of the preparations except 18. 



"Annual rt 

 Journal, vol. 2, 



rt of Uie Connecticut At 



I.. 27. 



Utur.il Experiment Station fur 187 



