176 Aluminium- 



microscope, the pillars or fragments of the corrugated sheet 

 dissolve first ; while the portions of the floors do not change 

 their form, for although much carbonate of lime is removed, 

 the animal membrane remains. The back of the shell dissolves 

 quickly, and the glassy-looking film behind it is converted in a 

 few minutes into a tough transparent material like gelatine 

 paper. 



Our polariscope object was composed of the floors, which 

 furnished the amorphous fragments of dull speckled golden 

 hue, while the corrugated supports supplied the portions that 

 glowed with the rainbow lights. If mere splendour is required, 

 the particles of the flooring should be rejected, and pieces of 

 the corrugations mounted alone, taking care not to spoil the 

 effect by breaking them up too small. 



It is interesting to find the vital and chemical processes by 

 which the cuttle shell is formed, combining to produce upon 

 the principle of corrugation that strength associated with light- 

 ness, which man, in his recent inventions, seeks to obtain in 

 precisely the same way. Hundreds of similar illustrations 

 might be given, of reason obtaining by slow degrees, and mani- 

 fold experiments, to methods of construction which abound in 

 the organic world. Sometimes the human contrivance is 

 assuredly an imitation, but oftener it is reached by an original 

 method, and when this is the case it is impossible not to be 

 struck with the evidence thus afforded of the unity of plan in 

 creation, as displayed in the intimate correspondence, or rela- 

 tion, that exists between the tendencies of human thought and 

 the processes, consciously or unconsciously, carried on in the 

 lower spheres of material existence, or of subordinate animated 

 being. 



ALUMINIUM. 



BY J. W. M f GAULEY. 



There is no subject connected with chemistry of more impor- 

 tance than that of the metals : nor is it an exaggeration to 

 assert, that they have been the principal agents in civilization. 

 We are chiefly indebted for the latter, however, not to those 

 which are costly and rare, but to that which, by a beneficent 

 dispensation of Providence, is the most common of them all : 

 since iron has been of far more value to mankind than gold. 



The ancients were acquainted with but few metals. In very 

 remote antiquity, metallurgical knowledge was almost confined 

 to copper and tin, which were more easily reduced than iron. 

 And, as it was soon discovered that some of their alloys were 



