160 REPORTS ON THE STATE OF SCIENCE.—1918. 
but as their presence is accidental, if it could be avoided it would 
clearly be to the benefit of the patient. 
By the use of certain colloidal preparations it is possible to 
attain this desideratum and to restore the organism to its normal 
state of ionisation in a relatively simple manner, without the com- 
plexities caused by the presence of unwanted ions. Thus, an 
anemic patient will be assisted by the administration of iron in a 
form in which the amount of hemoglobin in the system can be 
increased, but the administration of excessive doses of an unsuitable 
compound of iron will be useless for this purpose and will be 
detrimental in other ways, such as disturbing the digestive functions. 
The introduction of a soluble salt of iron into the serum will not 
necessarily increase the amount of hemoglobin, though the organism 
has a remarkable power of utilising apparently unsuitable materials. 
Briefly, it does this by first extracting some of the required agent 
(as when the gastric juices dissolve the ferrous carbonate in a Blaud’s 
pill), then, as the solution is usually very dilute, the agent becomes 
dissociated and the required ions are utilised by the organism and 
unnecessary ones being eventually discharged. It is obvious, how- 
ever, that if a therapeutic agent is presented in the form in which it 
is required—which in the case of many substances is in the state of 
a colloidal sol—much unnecessary waste of vital energy is avoided, 
the specific action is more direct and efficient, a loss of time which 
must occur before the body has effected the preliminary conversion 
is saved, and troublesome, or even dangerous, side reactions are 
avoided. 
The difference between the action of many medicines and the 
corresponding colloidal sols is remarkable. Thus, a 2 per cent. 
solution of iodine in either alcohol or potassium iodide stains the 
skin badly, and when administered internally is very liable to give 
rise to iodism. This is avoided by using a colloidal solution of 
iodine of the same or even greater concentration. 
It is, of course, of the utmost importance that colloidal medicines 
shall be in a suitable state. Colloidal gels are of value in certain 
cases, but far more important are the colloidal sols. The latter are 
difficult to prepare in a stable form, and unless they are resistant to 
the action of the electrolytes normally present in serum they are use- 
less for therapeutic purposes, as they would be precipitated before 
they could effect the desired purpose. Fortunately, it is easy to test 
the stability of a colloidal sol by examining it under the ultra-micro- 
scope after mixing it with various solutions in respect of which its 
stability may be questioned. 
Colloidal medicines which have not been prepared in a proper 
manner also decompose on long standing. They then show a precipi- 
tate, the amount of which increases as the decomposition continues. 
Properly-prepared, stabilised colloidal sols are quite permanent. 
The writer has kept collosol iodine and collosol silver for two years 
at a temperature of 70°F., and on examining them under the ultra- 
microscope at the end of this period could observe no difference in 
activity as compared with that of freshly prepared collosol. On the 
other hand, a colloidal silver prepared by Bredig’s method was feeble 
after four weeks and inert after seven weeks when kept under the 
