DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 231 
member of the series, it is obvious that the ten equivalents of carbon and five of 
hydrogen which it contains must be distributed among these three substances; 
and although we cannot, without further researches, determine how they are 
distributed, it is at least sufficiently obvious that the choice among different spe- 
culative arrangements is by no means large. In fact, our knowledge of the 
laws governing the constitution of organic compounds, enables us to see that the 
total number of possible permutations} of the elements of pyridine is only eight. 
They are as follows :— 
* 
C,H) 0, H,) C,H ©, 1) 
Ci HtN ci HSN cH SN 0, TN. 
care) C,H) C; H, C; H, 
*% * - 
C, H, cH) C, H C, H 
GBs ity C,H IN 0; TN. 
C, H,  H, 
Involving the feiliull of the chon nine radicals, all, pity the exception of 
methyl, at present unknown :— 
C, H, C, H, C, Hi, 
C, H, C, H, C, H, 
C,H C,H C, H 
Of these, two at least, C, H and C, H, are so extremely improbable, that we 
may, without much hesitation, pronounce against them; and if so, the probable 
formulee of pyridine are reduced to those marked with an asterisk. The question 
__ for consideration is, whether even these can be supposed to represent the constitu- 
tion of the base in a feasible manner. On this point no experimental evidence can 
at present be adduced ; but taking into account all the circumstances connected 
with them, my impression is, that none of them give the rational expression of its 
constitution, and that pyridine and its homologues belong to a class of bases of 
which we have as yet no other examples. 
In illustration of this opinion, it is necessary to enter into some details re- 
garding the constitution of the bases generally. It is scarcely necessary to remind 
the reader that when Horrman described his two new series of volatile alkaloids, 
he applied to those already known the name of amide, and to the new series 
those of imide and nitryl bases. This nomenclature, which has been more than 
once employed in the preceding pages, was founded on the analogy in constitu- 
tion of those substances with the well-known amides, imides, and nitryls. A 
very little consideration, however, suffices to show that this analogy is by no 
means complete. The first series of bases may be correctly compared to the 
amides, but the other two have no close resemblance to the imides and nitryls. 
On the contrary, they are strictly comparable with the secondary and tertiary 
’ 
+ I assume, with Grruarpr, that the number of atoms of carbon in any radical must always be 
diyisible by two. 
VOL. XXI. PART I. 3Q 
