SIR B. C. BRODIE ON THE CALCULUS OF CHEMICAL OPERATIONS. 
79 
for there is no property of a chemical phenomenon which compels us to regard it either 
from the one or the other point of view. In this respect the use made of the terms “ simple 
event ” and “ compound event ” is analogous to the use made in the first part of this 
memoir of the terms “ simple weight ” and “ compound weight,” a division coextensive 
with that into “ distributed ” and “ undistributed ” weights (I. Sec. I. 7, 8, 12). For not 
only are these terms dependent upon one another, a “ simple weight ” being defined as a 
“ weight ” which is not “ compound,” but they also have reference to some special system 
of phenomena considered from a definite point of view — a “ distributed” weight being a 
weight which in such a system of events is resolved into two or more weights, or made 
up from such weights, and an “ undistributed ” weight being a weight which in the same 
system of events is not so resolved or so made up,” there being nothing whatever in the 
properties of matter, apart from such considerations, to justify the use and application 
of such terms at all. Hence a “ weight ” which from one point of view and in one 
system of events is regarded as a “ compound ” and “ distributed ” weight, from another 
point of view and in another system of events may, with equal reason, be regarded as a 
“simple” or “undistributed” weight. These conceptions have their origin in the con- 
sideration of the chemical properties of matter, but may be transferred without any 
fundamental alteration of meaning from matter to phenomena, or “ the changes of 
matter ” — the symbol of a compound event being the symbol of one event which is 
“ an aggregate ” or collection of some other events, precisely as the symbol of the unit 
of hydrochloric acid is the symbol of one operation which is a combination of the 
two operations a and As it is essential that a correct appreciation should be made of 
what is here meant by a compound event, I shall proceed to give some examples of such 
events. 
Example (1). — Let us suppose ourselves to be informed that a unit of binoxide of 
hydrogen is identical with a unit of hydrogen and a unit of oxygen, that is to say, that 
i+«r=:«+f ; (1) 
this information could only be derived from the circumstance that the event of the 
transformation of a unit of binoxide of hydrogen into a unit of hydrogen and a unit of 
oxygen had, in some system of chemical metamorphoses, actually occurred, and the 
above equation informs us of all the circumstances of that event (as regards the identities 
of matter and space) which the event involves. Noav if no other information than this, 
either real or theoretical, be laid before us, we can form but one judgment as to that 
event, namely, that it is a “ simple event ;” for we are supplied with no information 
which enables us to regard it as a “ compound event,” and a “ simple event” is an event 
which, in relation to our information, is not compound. But let us also be informed of 
the two following circumstances, namely, that two units of binoxide of hydrogen are 
identical with two units of water and a unit of oxygen, and also that two units of water 
are identical with two units of hydrogen and a unit of oxygen. The events whence this 
information was derived are thus recorded : — 
