344 KANSAS CITY REVIEW OF SCIENCE. 



to pour from the first vessel into tlie next, the second into the third, and so on. 

 Numberless other combinations can be made. 



To make two colored solutions produce a colorless one we may avail our- 

 selves of the power possessed by nitric acid of bleaching indigo. Two solutions 

 of indigo are made \ one contains a good quantity of sulphuric and hydrochloric 

 acids, the other contains potassic or sodic nitrate. On pouring them together 

 and warming a colorless solution results, as the sulphuric acid sets free nitric 

 acide and chlorine, which destroys the indigo. 



Two liquids are to produce a solid. This is another double decomposition. 

 Saturated solutions of calcic chloride and potassic carbonate are poured together, 

 when a very heavy precipitate of calcic carbonate or chalk, is thrown down. At 

 the present time this seems rather a weak affair, but in its day it was called a 

 chemical miracle. It is for this reason that 1 show it to you. It is historic. 



Two gasses may produce a solid. This is effected by a simple combination. 

 Ammoniacal gas and hydrochloric acid gas are both absolutely gaseous at ordinary 

 temperature and pressure. If brought together they combine, forming a white 

 solid substance called ammonic chloride or sal ammoniac. It is the substance 

 used by tinsmiths to brighten the faces of their soldering bolts before tinning 

 them. 



If we immerse the bulbs of two thermometers, one in quicklime and the other 

 in ammonic nitrate, and add water to each, contrary effects are produced. The 

 quicklime has a strong affinity for water, and combines with it eagerly with evo- 

 lution of much heat. The nitrate of ammonia, on the other hand, without much 

 affinity for water, is very soluble, so it dissolves quickly, and in its passage from 

 the solid to the liquid state renders latent or absorbs a great quantity of heat, 

 causing a fall in the temperature, if rightly managed, of forty degrees. It is a 

 very instructive experiment. To make it really impressive the water should be 

 added from the same fliask, so that there can be n^d fear that water of different 

 temperatures is made to effect the result. 



We now come to some phenomena of combustion. As we generally see it, 

 it takes place in the air, which supplies the oxygen. But we can substitute for the 

 oxygen of the air that of a highly oxidized salt such as potassic chlorate. If we 

 mix this with sulphur, which is very combustible, and rub the two in a mortar 

 we get a series of quite violent detonations. By the use of phosphorus instead 

 of sulphur we have a still more violent explosive, which has to be handled with 

 more care. The products of these reactions are primarily sulphurous and sul- 

 phuric and phosphoric oxides. 



If we mix the same chlorate of potash with a proper proportion of sugar we 

 have a mixture that the touch of a match will ignite and burn with great splendor. 

 The carbon of the sugar unites with the oxygen of the salt. But it is quite un- 

 necessary to use fire to start it. A drop of oil of vitrol or sulphuric acid will 

 start the reaction, so that the deflagration will take place by decomposing the 

 chlorate. Thus we have a solid set on fire by contact with a liquid. 



