66 Boundary between Man |January, 
Very similar has been the case with the classification of 
the simple or elementary bodies. The science of the past had 
here, also, its dichotomous arrangement ; metals and non- 
metallic bodies, or, as the French and Germans call them, 
metalloids. To apply the term metalloid to a body which is 
all the time proclaimed eminently unlike a metal is one of 
the curiosities of scientific nomenclature. To fence in these 
two classes with strict definitions, and to assign to every 
element its place in one or the other, were tasks on which 
learning and research were freely spent. And what is the 
result ? That now there are several elements which forma 
debateable land between the two classes; that the love of 
paradox has caused one of the very bodies from which the 
idea of metal was originally obtained to be proclaimed non- 
metallic; and that the most truly philosophic chemists are 
beginning to regard the whole question as comparatively 
unimportant. 
Turning to Physics, we may be reminded that “‘ heat and 
cold’? were once viewed as distinét and antithetical forces. 
The zero of our ordinary English thermometrical scale is a 
fossil remnant of this supposition. At 32 degrees below the 
freezing-point of water it was held that there was an abso- 
lute privation of heat, and that below this only greater or 
less degrees of cold could be experienced. Now every man 
of science, every person of decent education,—always ex- 
cepting the author of ‘‘ Trinology,”’—conceives of cold 
merely as a degree of heat which is low in relation to his 
feelings, or to his general experience. 
Let us look next at the antithesis ‘“‘ vegetable and animal,” 
somewhile accepted without demur. We have still no diffi- 
culty in distinguishing the higher forms of “‘ kingdom,” as 
they are inaptly designated. We do not confound the eagle 
with the oak, or the donkey with the thistle. But on the 
confines there is here, again, a debateable land across which 
man has hitherto been unable—and finds himself from day 
to day less able—to erect one of those sharp, glaring, 
property-like fences in which his soul delights. An appeal 
was made to chemistry to find some absolute distinction 
between animals and plants. For a time the appeal seemed 
likely to be successful. We were told that animal matter 
contained nitrogen, which was wanting in vegetables. But 
soon nitrogenous bodies analogous to albumen and caseine 
were found in the seeds and in the juices of plants. It had 
been said that animal matter exposed to destructive distilla- 
tion yielded ammonia, whilst by treating vegetable substances 
in a similar manner acetic acid was obtained ; yet 99-1rooths 
