418 Reflections on some Mwefaidgicat SystcrM* 



art of merely and simply recognising them, the principal re- 

 sources must be drawn from the external characters. Wer- 

 ner engages his pupils to use them to the almost total ex- 

 clusion of any other succour. They are enjoined to confine 

 themselves as much as possible to the limits of their senses; 

 the use of the microscope is prohibited, and the world which 

 exists beyond their organs must not be viewed by them. 

 They must not employ a drop of acid, to determine whether 

 a body effervesces with it, till the last extremity*. The 

 strong light of the sun, used to discover sparkling, ought to 

 be considered but as a microscopic mean which is not al- 

 ways in our power, Almost every thing that nature or art 

 offers to facilitate our researches is denied, and we are re- 

 duced to the simple light of the day and our five senses. 



M. Hauy, after having founded the specification on the 

 form and composition of the integral molecule, adduces 

 means of attaining the diagnosis more easy and more 

 prompt thai, the inquiry into that form or composition. It 

 is true, he takes litile pains to describe ; and he does well, 

 because he can define ; but besides the character taken from 

 the integral molecule, he adds others with which physics and 

 chemistry have furnished him. Thus, for borated magnesia 

 we have as a ^eonielric character the cube; but this figure is 

 a term or limit, and consequently is common to other mine- 

 rals. Physical characters are therefore added ; as specific 

 gravity, hardness, elasticity, and a chemical character drawn 

 from the appearances w hen exposed to the action of the 

 blow- pipe. All the more striking characters are given to- 

 gether, which tend directly and absolutely to separate the 

 substances with which they might be confounded in conse- 

 quence of*the identity of form in the integral molecule. 

 This method, indeed, requires some physical and chemical 

 knowledge, while that of Werner dispenses with it sur- 

 prisingly. 



WERNERIAN ESTIMATE OF SPECIFIC GRAVITY AND OP 

 ANGLES. 



In (he particular exposition given by Werner of the ex- 

 ternal characters, he treats in the first place of colour. This 

 made many persons believe that he considered it as a principal 

 character, and drew on him reproaches from which I hasten 



* Hence, doubtless, the reason that the disciples of Werner are all so furi- 

 ously hostile to chemistry, that they are so limited in their pursuits, so con- 

 tracced in their notions, and so deficient in those principles of general science 

 which contribute to meliorate the state of human existence, and improve so- 

 ciety. — Trans. 



to 



