CHEMISTRY. 3 
product, or property, each involving some chemical] difference, to give him 
some idea of how numerous the various combinations of elementary matter 
must be. The same consideration will also suggest how varied must be 
the experience to be collected by chemistry, and how diversified the 
experiments by which she ascertains her facts. With the progress of any 
science, the amount of its elucidatory and accessory apparatus increases, 
the latter being the true exponent of the former. In this view, a description 
of chemical apparatus, and of its application, will give us an idea of the 
present state of the great science of modern chemistry. 
1. Conprrions or AGGREGATION oF Marrer. 
All ponderable matter, whether belonging to the mineral, to the vegetable, 
or to the animal kingdom, presents itself to us under one of three conditions 
of aggregation, depending on the temperature and pressure to which the 
body may be subjected. These states of matter are the solid, the liquid, and 
the gaseous. 
The four elements of Anaximander, earth, water, air, fire, illustrate 
the difference between the idea of an element as entertained by the ancients 
and by the modern philosopher. The elements of the former, instead of 
expressing the elementary simple ingredients of which all bodies are 
composed, merely typified the three states of matter, earth answering to the 
solid, water to the liquid, and air to the gaseous. The fourth element, fire, 
may be considered as symbolizing the effects of the imponderable agents, 
heat, light, magnetism, and electricity. 
We may safely assume that all solids are capable of being changed into 
liquids and gases, by the application of the proper agencies. It is well 
known that many of these solids are capable of this transformation, as seen 
in the conversion of the solid lump of ice, by the simple application of heat, 
into the liquid, water, and finally into the gas, steam. The fact, however, 
is not so generally appreciated that gold may be vaporized by the focal heat 
of a large mirror, and that the apparently infusible platinum, the metal 
which can withstand the furnace seven times heated, is speedily made to 
boil and disappear by the flame of the oxy-hydrogen blowpipe. We may 
therefore assume that all solids are capable of these transformations by the 
increase of heat and diminution of pressure. The converse is also most 
probably true, to the same extent, that all gaseous matter may be converted 
to solid by the diminution of heat and increase of pressure. In many 
cases, either heat or pressure, applied positively or negatively, may suffice ; 
in others, both are required ; and if they produce the desired effect neither 
singly nor incombination, we may analogically conclude that it is because 
of the inadequacy of our means, and not of the impossibility of the end. 
ICONOGRAPHIC ENCYCLOPADIA.—VOL. f. 28 433 
