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BRITISH PHARMACEUTICAL CONFERENCE. 
one ; all emulsions separate into two parts in the course of time, and we cannot 
say exactly how slow the separation should be to entitle the mixture to be con¬ 
sidered an emulsion. Nor is there any evident reason why other fluids, or 
fluids and solids, mixing in a similar way, should not be considered emulsions. 
Milk and chyle may be considered animal emulsions, and the juices of Taraxa¬ 
cum, Clielidonium , or Ficus elastica may be regarded as natural emulsions from 
the vegetable kingdom; and we would not wait till we had ascertained the 
length of time required for the separation of their parts, not till analysis had 
proved the nature of their proximate constituents, before pronouncing them 
members of the emulsion family. My first queries were in reference to the 
state or mechanical nature of the mixture. I asked myself, are the suspended 
particles always spheroidal ? If not, are emulsions more perfect when they 
are so ? J 
Then a series of chemical questions arose. Do alkalies promote and acids 
hinder emulsifaction ? Are the naturally emulsible gum resins neutral ? Then 
a group of physical problems, such as the relation between colloid and crystal¬ 
loid conditions and emulsibility, and the questions, do substances which pro¬ 
mote frothing, the mechanical division of air, also promote emulsifaction, the 
mechanical division of oil, etc. ? These, with many ether questions, appeared 
to occupy an ample field for both inductive and deductive work, in which I had 
hoped to establish a few interesting principles, and, by the application of these 
principles, to lay down a few general rules of practical utility to the pharmaceu¬ 
tist. I commenced work by experimenting upon simple oils and water, without 
addition. 
Taking an ^iss phial, and putting into it half an ounce distilled water, and 
1 drachm olive oil; shaking them together, and noting the kind of mixture and 
the time required for separation ; then adding oil, drachm by drachm,—making 
the observations till there were 6 drachms of oil to 4 of water. Then commencing 
again with 4 drachms of oil to one of water, the reverse of the proportions first 
mixed, repeating the observations, step by step, as water was added, drachm by 
drachm, up to 4 drachms. Had I been able to devote the requisite time to the 
subject, I should have made similar experiments with almond oil, castor oil, lin¬ 
seed oil, balsam of copaiba, and other materials, as they suggested themselves, 
and then proceeded to ascertain the effects of introducing other chemical or me¬ 
chanical elements into the operation; but the series of observations which thus 
should have been counted by hundreds, was unexpectedly cut short before it 
leached the tenth of its expected dimensions, and I have now only to draw your 
attention to two or three points which already bear some interest. 
M hen olive oil was added to water, the mixture separated most slowly when 
the proportion was o drachms of oil to 4 of water, the time required increasing 
with each drachm of oil up to this proportion, and again decreasing with further 
ac ditions, till the proportion was 6 of oil to 4 of water. When water was added 
to olive oil, the separation takes place much more slowly than in the former case 
+-u ’ , wlien ^ ^ad been added drachm by drachm, with agitation at each step, 
if there were equal parts of each, the separation took place only in several 
lours, instead of as many minutes, which had sufficed i*n the former case. And 
thei e was no less difference in the mixing than in the separating. In the first 
series the mixing, as far as the fluids seemed likely to mix, was effected by a few 
seconds of brisk agitation ; but, in the second series, a quarter of an hour’s agi¬ 
tation or more was required to effect the mixture of the third and fourth drachm 
of water, and, when it did take place, the mixture became so thick, that it would 
not rattle when the bottle was violently shaken. A careful examination of two 
mixtures, each containing equal parts of oil and water, but, in the one case, the 
01 hemg added drachm by drachm to the water, with agitation between each 
addition, and, in the other, the water being added in like manner to the oil, 
