32 SCIENCE PROGRESS 



we may note that M. de Lapparent * is content to attribute 

 early observations on this matter to Kreil (1849), who also 

 worked among the Alps, and to Locke (1846), who made 

 investigations in North America. 



Korda 2 states that as early as 1778 Brugman, of Leyden, 

 had described many minerals as being magnetic, including 

 those which contained iron and cobalt. The same author 

 states that in 1792 Fullerton obtained in England a patent 

 for separating magnetic from non-magnetic materials by means 

 of permanent magnets. 



The geologists of this period were familiar with the wide 

 distribution of magnetite in eruptive rocks ; they were in the 

 habit of extracting it from crushed rocks by means of a magnet, 

 and of noticing that the rocks which contained it affected the 

 magnetic needle. In 1794 Dolomieu 3 characterised his group 

 of compact basic volcanic rocks as having, among other things, 

 a marked effect on the magnetic needle. He observed that 

 specimens of certain lavas exhibited a well-marked polarity, 

 which was retained by the fragments when the specimen was 

 broken. 



In 1800 Bellevue 4 recommended the partial crushing (demi- 

 trituration) of rocks, and mechanical analysis {analyse mecan- 

 ique) of the fragments, including elutriation and treatment with 

 a bar magnet. In this way he made a thorough examination 

 of the leucite-nepheline-melilite-basalt of Capo-di-Bove, making 

 a fairly full record of its mineral composition. He concluded 

 his interesting memoir by stating his belief, that the adoption of 

 the methods he describes would be a potent means of discovering 

 new minerals, and of elucidating the nature of rocks. It is 

 instructive to note the acute observations made by these early 

 workers, and not a little surprising to find that they achieved 

 so much with the limited means at their disposal. Bellevue 

 especially emphasised the importance of examining the sands 

 which had resulted from the disintegration of rock masses. 



As if to show that he had appreciated the importance of 



1 Traite de ge'ologie, 1906, tome i. p. 106. 



2 La separation electro?nagnetique et electrostatique des minerals, Paris, 1905. 



3 "Suite de memoire pour servir d'explication a. la distribution methodique de 

 tous les produits volcaniques," Journal de Physique, etc., 1794. 



4 " Memoire sur les cristaux microscopiques," Journal de Physique, tome li. 

 1800. 



