140 
It is very probable, and almost admitted by Kékulé, that 
kresol is monomethylated phenol and phlorol bimethylated 
phenol. In the same way may we feel entitled to consider 
guajacol monomethylated pyrocatechin and kreosol bimethy- 
lated pyrocatechin; in fact, in treating guajacol with hydri- 
odic acid we obtain iodide of methyl and pyrocatechin, which 
amounts to a proof of this view, and which gives us therefore 
two links, by which we may connect the series of coal-tar 
oils with those of wood tar. To render it apparent to the 
eye I will give the formule, as follows :— 
C,H,(OH) Phenol. C,H, (OH) Pyrocatechin. 
CO Eby 1 te Kresol, C,H,0} ne Guajacol. 
3 3 
OH OH. 
C,H; < CH, Phlorol. C,H,0 4 CH, Kresol. 
C C 
3 3 
it may be stated, as a further proof for the correctness of 
considering the above compounds as methylated pyrocatechin, 
that the molecule of methylene, CH,, may be introduced 
directly into the constitution of pyrocatechin, by heating itin 
closed tubes with caustic potassa and methylsulphate of pot- 
assa, producing thereby guajacol. 
The homologues of the phenylic series are crystallizable 
compounds, of the respective boiling points of 184°C., 203°C., 
220°C., while the two derivatives of pyrocatechin are oily 
liquids, boiling at a temperature of 200°C. and 219°C. 
Phenol, 184°C. Pyrocatechin, 
Kresol, 203°C. Guajacol, 200°C. 
Phlorol, 220°C. Kreosol. 219°C. 
It may be seen, therefore, that in cases of working with a 
mixture of the individuals of both series, we should find it 
impossible to separate them by fractional distillation, 
Their products of decomposition, however, may be resorted 
to as a means of distinguishing between them. For while 
phenol and its series yields with nitric acid nitrophenol and 
similar compounds, we obtain with guajacol oxalic acid ; 
chlorine converts phenol into chlorophenie acid and chloranil, 
while the products obtained in this way from creosote, 
though similar to them, present differences which stamp them 
as peculiar and distinct bodies. 
