On Marine Dredging^ 361 



and which, cunsequeutly, are not to be seen in any museum or col- 

 lection. Thu main ingredient made use of is bay salt, a minute 

 quantity of corrosive sublimate, about two grains to a quart of the 

 solution being added to prevent vegetation. There can be no doubt 

 of its success, provided the necessary care and attention arc bestow- 

 ed ; but it is necessary first to use a weak solution, repeatedly 

 changing it to a stronger, till it is nearly saturated with bay salt. 

 The time required for this is the only drawback, as on an expedition, 

 where there would be sufficient employment for a naturalist follow- 

 ing the ordinary plan, there would bo abundant occupation for an- 

 other individual in preserving the objects in a way to do them justice. 

 Alum is occasionally added to the solution with advantage, where 

 there is no carbonate of lime contained in the specimen to be pre- 

 served, but the use of it requires some practical experience ; and in- 

 deed no rules can be given capable of being applied generally, as most 

 classes of animals require, more or less, a particular treatment. 



On the several Volcanic interferences^ which alternate and are 

 concurrent rvith, and eventually supersede, the depositions of 

 the Old Red Sandstone of the British Isles. By the Rev. D. 

 Williams, M.A., Corresponding Member of the Geologi- 

 cal Society of Cornwall. Communicated by the Author. 



If I am right in the views which I have briefly announced 

 in some former publications, that the whole multifarious and 

 Protean family of the so-called " Plutonic and igneous rocks,*** 

 with their universally-associated trappaean ash and slate re- 

 lations, are simply volcanic products, commonly submarine, 

 and had their origin in chemically-generated heat (for which 

 by the way I ask for and invoke no imaginary masses of po- 

 tassium or other unoxidized metallic bases) — chemically-ge- 

 nerated heat, perfectly apart from fire or combustion ; — that 

 the granite and trappaean vein-like ramifications that so com- 

 monly penetrate the rocks which bound them, and have en- 

 tailed on them, to various extents and depths, the ravages of 

 reduction they now exhibit, in all its stages from perfect fusion 

 to semi-fusion and remote incipient induration. — If those so- 

 called veins, and that amount of alteration, be existing 

 monuments of the processes by which the imprisoned and accu- 

 mulating high temperature reduced those bounding rocks. — 

 If the different granite, porphyry, or hypersthene bosses, be 



