1 70 MEMOIR OF DR. DALTON, AND 



" Seven earths, capable of forming ductile metals. 



" Seven earths, capable of forming metals not ductile. 



" Seven earths, incapable of forming metal. 



Question 1. Is there but one earthy element, which, in 

 various modes of aggregation, or in indissoluble combination 

 with other elementary matter, forms twenty-one earthy bodies? 

 or. Question 2, Are there three times seven, or seven times 

 seven earthy elements? 



Page 15. " Experimental and geometrical estimation of the 

 force of this attraction in fortuitous arrangement of the atoms, 

 and of the force of this attraction in the polar arrangement of 

 the atoms. 



On attraction he says, page 23, " That no element doth 

 saturate, nor can saturate, the like element ; that no element, 

 whose atoms attract each other, can saturate any other element 

 whose atoms attract each other ; that a repellent element doth 

 saturate non-repellent elements, and vice versa ; that repellent 

 elements do saturate reciprocally; and that attraction and 

 repulsion, operating adversely, are the cause of saturation; 

 and saturation is not a distinct or primary law of nature, but 

 an effect." 



We find here no ideas given of definite compounds, except 

 so far as the ordinary idea of saturation is concerned. Had 

 Dr. Higgins any theory resembling the present atomic theory, 

 he would certainly not have expressed himself so darkly on 

 the subject of saturation. 



We even find that he is not quite freed from the prima 

 materia^ although he restricts it to the matter of certain 

 classes, such as the matter of earth forming many earths, the 

 acid matter forming many acids. He is, therefore, to be 

 viewed as one bordering on the transmutation theory, not 

 freed from mystic ideas, but grappling with the subject so 

 energetically, that in some directions he almost sees his way 

 into another region of theory. 



I shall quote the most important sentences in the *'Experi- 



