• SCIENTIFIC SUMMARY. 
657 
— nicotine — is developed in tobacco during the fermenting process to which 
the leaves are subjected ; but it wmuld appear from some recent researches 
that the narcotic and stimulant ingredients exist in the green plant. Mr. 
Ferdinand F. Mayer, of New York, who has completed a number of experi- 
ments on this subject, has arrived at the following conclusions : — 1st, That 
nicotina is the active principle in all parts of the tobacco-plant, both before 
and after “ curing ” ; 2nd, that there is in all probability no increase, but 
rather a loss, of nicotina during the drying and “ curing,” partly or wholly 
caused by volatilization ; and 3rd, that the plant and its parts contain no 
trimethyline nor ammonia while in the fresh state. 
Constitution of the Niobium Compounds. — At a late meeting of the French 
Academy of Sciences, MM. Saint-Clare Deville and L. Troost gave the 
result of their critical researches on the constitution of the compounds of 
niobium. The authors believing with M. Marignac, that Kose’s hypochloride 
of niobium and the hypofluoniobates contain oxygen, have experimentally 
investigated this point, and draw the following conclusions from their 
analyses : 1. Kose’s hypochloride of niobium should be considered as an 
oxychloride. 2. All the extraordinary properties of niobium come under 
a common law. The oxychloride of niobium is a body which crystallizes in 
large uncoloured silky tufts. Its vapour-density, from the mean of two 
experiments, the authors found to be 7’88. 
An economic Method of employing the Magnesium Light has been devised 
by Signor Carlevaris, of Mondovi. He stated, in a recent memoir, that 
when magnesium wire was ignited in atmospheric air, or pure oxygen, the 
most luminous effects were not manifest till a certain quantity of oxide had 
been formed, and was Taised by the heat produced to an exceedingly high 
temperature. The light in this case, as in the combustion of carburetted 
hydrogen, as in that of hydrogen in contact with platinum, and as in the 
Drummond arrangement, is derived from the solid particles raised by tlie 
flame to a great heat — a heat which dissolves and volatilizes platinum, but 
leaves the oxide of magnesium solid, fixed, and intact. To raise this oxide 
to the temperature necessary to give the greatest light, it should be presented 
to the flame in as small a quantity and as large a volume as possible, which 
is done by employing a spongy oxide obtained as follows : — A piece of 
chloride of magnesium is exposed to the flame of the oxyhydrogen blow- 
pipe, in contact with a piece of carbon. The chloride of magnesium is 
rapidly decomposed, leaving the spongy oxide, which gives the light in 
question. 
A new Modification of Gun-cotton has been prepared by M. Blondeau, and 
described by him in an important paper presented to the French Academy. 
This new kind of pyroxylene is said to possess a much higher explosive 
power than the ordinary kind, and, in addition to this, is unalterable, not 
only at the ordinary temperature, but does not decompose at 212°. To 
bestow these virtues upon gun-cotton, it is only necessary to take a good 
specimen of the usual sort, and expose it for about four hours to the action 
of ammoniacal vapours. The gun-cotton becomes yellow, and a compound 
has been formed with the ammonia, having no less a formula than 
H^q, Ogy, 4(NO.) (NO^) (NHg). This body, Avhen dried, forms a 
