Page:Various Forces of Matter.djvu/190

178 It produces deep red fumes as soon as it comes in contact with the air, by combining with the oxygen of the latter to form hyponitrous acid. Binoxide of nitrogen is composed of two parts oxygen and one part of nitrogen; hyponitrous acid is composed of one part of nitrogen and three parts of oxygen.

LECTURE IV.

($17$) Page 91. Chlorate of Potash and Sulpuret of Antimony. Great care must be taken in mixing these substances, as the mixture is dangerously explosive. They must be powdered separately and mixed together with a feather on a sheet of paper, or by passing them several times through a small sieve.

($18$) Page 92. The mixture of chlorate of potash and sugar does not require the same precautions. They may be rubbed together in a pestle and mortar without fear. One part of chlorate of potash and three parts of sugar will answer. The mixture need only be touched with a glass rod dipped in oil of vitriol.

($19$) Page 92. Two salts dissolved in water. Sulphate of soda and chloride of calcium. The solutions must be saturated for the experiment to succeed well.

($20$) Page 96. Lead pyrophorous. This is tartrate of lead which has been heated in a glass tube to dull redness as long as vapours are emitted. As soon as they cease to be evolved the end of the tube is sealed, and it is allowed to cool.

($21$) Page 99. Gun cotton is made by immersing cotton-wool in a mixture of sulphuric acid and the strongest nitric acid, or of sulphuric acid and nitrate of potash.