FORMATION OF ENHYDROS OR W ATER- STONES . — COOKSEY. 93 
Victoria, and in a later paper in the same volume (page 71) Mr. 
George Foord more minutely described them, and also gave the 
results of a qualitative analysis of the liquid contained in one. 
He found it to be a dilute aqueous solution of chlorides and 
sulphates of calcium, magnesium and sodium, with a soluble form 
of silica. The author also sought to explain their formation on 
the supposition that a certain proportional mixture of colloidal 
and crystalline silica in solution might have a tendency on deposi- 
tion to assume a definite crystalline form. 
Prof. A. Liversidge, in the Records of the Australian Museum, 
p. 1 of the present volume, figured and described two large speci- 
mens acquired for our Collection, and suggested that they might 
possibly have been formed by the deposition of silica in hollows 
or cavities in clay which could have been caused by movements in 
the clay itself. I have not up to the present been able to find any 
other literature on the subject, with the exception of references 
to these bodies as pseudo-crystals, enhydros or water-stones. 
A further detailed description is therefore quite unnecessary, 
but their character may be briefly summed up as follows : — 
They consist usually of hollow quartz and chalcedonic forma- 
tions frequently containing liquid, and are bounded externally 
by smooth perfectly even surfaces meeting in well-formed sharp 
straight edges. Some of them from their external appearance 
might easily be mistaken for true crystals, but a closer examina 
tion shews that such cannot lie the case, for no two surfaces 
appear to correspond one with the other. This fact negatives 
the supposition that they might possibly be pseudomorphs. In 
some specimens the walls are formed entirely of chalcedony, in 
others the outer surface only is chalcedonic, while the interiors 
are either lined or completely filled up with quartz. 
Some exactly similar formations were also discovered in Iredell 
Co., N. Carolina, America, and seven specimens were sent to this 
Museum labelled quartz-pseudomorphs after calcite. They are 
exactly similar in every respect to those from JBeechworth, 
Victoria, with this exception, that five of these specimens are 
composed entirely of quartz, chalcedony appearing to have played 
no part whatever in their formation. The sizes of the enhydros 
in the possession of the Australian Museum range from that of 
half an inch to that of seven and one-eighth inches in length. 
Leaving out of consideration for the moment their geometric 
form, most of these enhydros shew such a striking resemblance 
to many agates, that one is naturally led to 1 tie conclusion that 
a similar mode of formation must be common to all. Prof. 
Liversidge’s suggestion that they may have been formed by 
the infilling of cavities in clay, seems to me to fail to account 
* Proceedings of the Royal Society of Victoria, X., p. 32, 
