ely soluble in the liquid; powdered niter melts at once in
contact with it, and the two liquids then mix. Free hydroxylamine is
without odor. It is heavier than water. When rapidly heated upon
platinum foil it suddenly decomposes in a most violent manner, with
production of a large sheet of bright yellow flame. It is only very
slightly soluble in liquid carbon compounds, such as chloroform,
benzene, ether, acetic ether, and carbon bisulphide. The vapor attacks
corks, so that the solid requires to be preserved in glass-stoppered
bottles. The free base appears also to act upon cellulose, for, upon
placing a few drops of the melted substance upon filter paper, a
considerable amount of heat is evolved. The pure crystals are very
stable, the base in the free state appearing to possess much greater
stability than when dissolved in water. The instability of the
solution appears, however, to be influenced to a considerable extent
by the alkalinity of the glass of the containing vessel, for
concentrated solutions free from dissolved alkali are found to be
perfectly stable. Bromine and iodine react in a remarkable manner with
free hydroxylamine.

Crystals of iodine dissolve instantly in contact with it, with
evolution of a gas and considerable rise of temperature. Bromine
reacts with violence, a gas again being explosively evolved and
hydrobromic acid formed. The nature of the gas evolved is now
undergoing investigation. A letter from M. Lobry de Bruyn appears in
the number of the _Chemiker Zeitung_ for October 31, warning those who
may attempt to prepare free hydroxylamine by the above method that it
is a dangerously explosive substance when warmed to a temperature of
80 deg.-100 deg.. Upon warming a flask containing the free solid base upon a
water bath a most violent explosion occurs. A spontaneous
decomposition appears to set in about 80 deg., and even in open vessels
the explosion is very violent. Care must also be taken during the
fractional distillation of the concentrated solution in methyl alcohol
to cool the apparatus before changing the receiver, as if air is
admitted while the retort is heated the experiment ends with an
explosion.--_Nature_.

* * * * *

THE SCIENTIFIC AMERICAN

ARCHITECTS AND BUILDERS EDITION

$2.50 a Year. Single Copies, 25 cts.

This is a Special Edition of the SCIENTIFIC AMERICAN, issued
monthly--on the first day of the month. Each number contains about
fo