]5G Scientific Intelligence. 



Faraday, but the vessels in these specimens, as he was informed, 

 were quite different from those of the recent sugar cane. 



The examples which appear to be of the most recent formation, are 

 some specimens from Loch Neagh, where fibrous portions of carbon- 

 aceous matter occur dispersed in different parts of silicified masses, 

 and the silicified Gorogonites, or seeds of the Chara hispida, de- 

 scribed by Mr. Lyell, from the lakes in Forfarshire. 



In referring to the explanation of these curious phenomena, Dr. 

 Fai'aday considered that the present state of our knowledge did not 

 enable us to afford a solution of the diffculty, and that to form a 

 theory would merely tend to embarass the subject, for such was the 

 universal character of theories. It is impossible to admit that intense 

 heat could have produced these changes, because Dr. McCulloch as- 

 serts that confervas exist in many specimens of rock crystal, which 

 would have been destroyed if the matter in which they lie enclosed 

 had been exposed to a high temperature. The views of Dr. Turner, 

 the lecturer considered, afforded an excellent explanation of the 

 source of the silica. He exposed portions of crown and window 

 glass to the action of steam in a high pressure boiler, the temperature 

 being 300° F. In the course of 4 months, they were found to be 

 more or less decomposed ; the white earthy portions were found to 

 be entirely free from alkaline matter, but the actual loss was not due 

 to the extraction of the alkaline matter only, for the silica of the glass 

 had also been dissolved, as was proved by the apertures of the wire 

 gauze in which the glass was incased, being filled up at the most 

 depending parts by a siliceous incrustation, where also a stalactitic 

 deposit of silica about an inch and a quarter long had formed. Dr. 

 Turner adduced these facts to illustrate the action of water at high 

 pressure on felspar, and other rocks containing alkaline matters. 

 Dr. Faraday considered these experiments as highly important in 

 regard to affording a source for the silica, but conceived that we were 

 still ignorant of the mode in which the silica is deposited in such a 

 variety of forms. He stated that he had brought the subject before 

 the meeting to stimulate to investigation respecting this interesting 

 and beautiful phenomenon. 



Note. — It may be observed, that excellent imitations of chalcedony 

 can be produced, by allowing silica, in the gelatinous state, to dry 

 on a filter in the open air. The following queries may not, perhaps, 

 be out of place : Is the opinion expressed by Dr. Faraday on the in- 

 fluence of theories altogether just? Have they not acted beneficially 

 on the developement of electricity, optics, and chemistry ? Does 

 the explanation suggested by Dr. Turner apply to the solution of 

 silica in any other situations than under great pressure, and conse- 

 quently at a great depth, and at a temperature above the boiling 

 point of water ? If it does not, why should silicified wood occur 

 only at the surface, and chiefly on siliceous and calcareous forma- 

 tions? — Edit. 



V. — Action of Acids upon Sugar. 

 Malaguti finds 1st. that both organic and inorganic acids act in the 

 same way upon sugar, when influenced by heat ; and that it is trans- 



