82 Dr. Rominger on Pleurodyctium problematicum. 
as Clin IC],. There is the same confusion between dibasic and 
Sathabasic radicles, as in CO. ence we infer that the ee sg 
between even and odd-basic is altogether superior to that 
tween monobasic and tribasic, dibasic and tetrabasic. 
Now if a body can enter into double decomposition with hy- 
drogen (that is, combine without condensation) it is obvious that 
ume of H unless it combines with two kts Tf it does thus 
combine it will be tribasic, otherwise mono 
On the other hand, if a a body cannot enter ite double decom- 
position with the monobasic radicles, it must be even- mae. for 
in this case, since its volume after combination will be th e sattie 
icle betaine a constituent in combination, it follows 
that its cea! forces do not come to equilibrium of ‘themselv: ves, 
and this accounts for the fact that monobasic radicles cannot ex- 
ist free. This fact is determined by reactions and not by vapor 
9. An odd-basic radicle i bee in itself out of sceniiatadl in 
this way, it follows that the addition of it to another radicle will 
change the basicity of that radicle from odd to even or from 
even to odd; while the addition of an even-basic radicle will 
have no such effect. 
ambridge, Mass., Dec. 1862. 
Art. XIII. Ts of the true nature of Plauradyetiom prob: 
lematicum ; by CARL Romincer, M. D. 
Unver the above name I have long kept in my cabinet a ae 
cimen, collected at Kirchweiler in the Eifel mountains. i 
having identified it with the fossil described by Goldfuss, I Iai 
it net; ang only recently, twenty years afterwards, when # 
to look over it again, the first glance convinced me that 
problematicum is merely the cap of a Favosiles, 
