ON COLLOID CHEMISTRY AND ITS INDUSTRIAL APPLICATIONS. 159 
Many of the recognised methods of treating disease are efforts 
made with a view to altering the colloidal state of some portion of 
the patient’s body, such as the reduction of a swelling by the de- 
hydration of an unduly hydrated gel or varying the amount of dis- 
persion of the colloidal particles in another part of the system. 
Thus, it is now quite recognised that many of the most familiar 
medicines are crude preparations of a colloidal character in which 
the action of the essential ingredient has been largely obscured by 
the presence of adventitious substances, some of which possess un- 
_ desirable or even toxic properties. The digestive disturbances caused 
by the administration of iron compounds, the headaches which 
accompany the administration of quinine, and the pain resulting 
from the use of silver compounds are well known examples of the 
interference of some subsidiary ingredient of an otherwise useful 
therapeutic agent. 
Many attempts have been made to avoid these complications. In 
some instances, remarkable results have followed the use of extremely 
dilute (7.e., fully ionised) solutions; other investigators have sought 
to eliminate the disturbing elements and to produce purer medicines, 
and others again have endeavoured to counteract the irritants by 
using two or more drugs in combination. Each of these methods 
has resulted in a certain amount of progress. For many years, how- 
ever, the essentially colloidal character of the recognised remedies 
was overlooked, and the fact was not realised that before a drug can 
exert its full therapeutic action it must be converted into the 
colloidal state. 
One of the earliest to appreciate the importance of using thera- 
peutic agents in a colloidal state was the late Henry Crookes who, 
in 1911, after making protracted experiments, found a means of pro- 
ducing stable preparations of colloidal silver, copper, iron and 
mereury which were not precipitated by saline solutions. To these 
he gave the name “Collosols.” Since that time, stable preparations 
of colloidal solutions of sulphur, iodine and manganese as well as 
those of a much more complex character including some of the 
alkaloids cocaine, etc., have been used extensively by leading medical 
practitioners with wholly satisfactory results. The use of unstable 
colloidal sols has, on the contrary, been far from satisfactory and has 
led to serious misconceptions as to the value of remedies in the 
colloidal state. 
Owing to their condition, stable colloidal sols behave in a manner 
quite different from other synthetic medicines. The latter—even 
when dissociated—contains two distinct groups of substances, one 
positive and the other negative. So far as is at present known, a 
diseased organism is deficient in either positive or negative ions, or 
it has an excess of one of these kinds of ion and is unable to get rid 
of it. The former case is much more common than the latter. The 
natural remedy is the presentation of further ions of such a character 
as to make good the deficiency or to remove the excess. If solutions 
_ of chemical compounds of a crystalline nature are administered they 
must first be dissociated and the requisite ions will then be available 
for use. The action of the ions which are opposite in character to 
those required by the body may be either disadvantageous or neutral, 
