On the Value of different lands of Vegetable Food. 365 



days they are hardly perceptible, though they never cease 

 altogether. On some days they are violent, if I may be 

 allowed the expression. The needle does not take a sudden 

 start and return as when influenced by lightning, but moves 

 gradually without oscillation to some fixed point, from which 

 it will return sometimes in two minutes and sometimes in ten 

 or fifteen minutes. An extended series of observations will be 

 necessary before any deductions can be safely made. If the 

 wires should be separated by a slight interval during a thunder 

 storm, doubtless electrical sparks would be visible. During 

 heavy storms, a flash of lightning twenty miles distant from 

 the wires of Morse's telegraph will induce electricity in the 

 wire sufficient to operate the magnets and work the telegraph, 

 sometimes recording several signals. A flash of lightning in 

 Baltimore, forty miles distant from this place, will operate the 

 magnet at this end of the line. 

 Washington, D. C. 



LVII. Value of different kinds of Vegetable Food, based upon 

 the amount of Nitrogen. By E. N. Horsford, M.A.* 



CINCE Gay-Lussac's discovery of nitrogen in the seeds of 

 ^ plants, the conception of animal nutrition has been assu- 

 ming a more and more definite character. 



Already have the principal proximate ingredients of meal, 

 by taking advantage of its physical properties, been separated 

 from each other. Gluten, albumen and legumine, starch, 

 gum, sugar, dextrine and woody-fibre, have been made known, 

 and their physical as well as some of their chemical proper- 

 ties t studied. Their more accurate chemical constitution 

 was reserved to a later period, when it was found that they 

 might be arranged in two classes, those containing nitrogen 

 and those containing no nitrogen ; and the interesting dis- 

 covery was made, that the former, as well as the latter, are 

 among themselves identical in composition. 



It is well known that labourers supplied only with food 

 containing no nitrogen, become incapable of executing their 

 tasks : and further, that the corporeal system, even without 

 labour, cannot be sustained upon such food. The discovery 

 of the near identity in chemical composition between vegetable 

 albumen, fibrine and caseine, and the corresponding bodies 



* Communicated by the Author. 



t Fr. Marcet found gluten consisting of 55*7 per cent, carbon, 22 per 

 cent, oxygen, 7'8 per cent, hydrogen, and 14*5 per cent, nitrogen. — Ann. 

 de Ch. et de Phys. xxxvi. 27. 



