FRAGMENTS OF SCIENCE. 



859 



shining may be extinguished, as M. llesnard 

 has shown, by the introduction of a quantity 

 of air inversely proportioned to the strength 

 with which it is charged with turpentine. 

 Spirit of turpentine may tlius be made a 

 common standard for the different essences, 

 and we may regard as the measure of the 

 intensity t)f the perfume disengaged by a 

 given weight of an essential oil the ratio be- 

 tween the weight of the turpentine which 

 will neutralize the perfume and the weight 

 of the same substance which under corre- 

 sponding conditions will act upon phosphor- 

 escence with corresponding energy. M. Mes- 

 uard has devised an ingenious apparatus for 

 performmg practical measurements by the 

 application of this principle. 



Cordite. — According to the Industrial 

 World, the manufacture of cordite is very 

 simple. Nitroglycerin and dried gun cotton 

 are mixed together in accurately weighed 

 portions, the liquid nitroglycerin being 

 poured over the gun cotton and mixed by 

 hand until it is all taken up by the cotton, 

 producing a dirty-white mass which looks 

 much like sugar. This mass is then placed 

 in kneading machines, which mix in the 

 proper proportion of acetone. After several 

 hours' kneading some vaseline is added and 

 mixed in by further kneading. The mass 

 finally becomes a stiff dough, which can be 

 readily molded into any desired shape. The 

 combination of nitroglycerin and gun cotton 

 with acetone produces a compound quite 

 different in appearance and properties from 

 either of its components. Cordite is a heavy 

 substance which burns only on the surface, 

 the violence of whose explosion can hence 

 be readily regulated by varying the relation 

 between surface area and volume. Both 

 nitroglycerin and gun cotton are very un- 

 stable. Cordite, on the other hand, is quite 

 the reverse. Thus, a bonfire made around 

 eight cases piled up against each other sim- 

 ply burned up the boxes and then the cor- 

 dite, no explosion occurring. 



Death of Prof. Ernst Cnrtins. — Dr. Ernst 

 Curtius, Professor of History and the Fine 

 Arts in the University of Berlin, who died 

 July 12th, aged eighty-one years, was one 

 of the most distinguished and most learned 

 historians and archaeologists of the century. 



He was born at Liibeck in 1814, of a family 

 distinguished by love for literature and art ; 

 studied at Bonn, Giittingen, and Berlin ; went 

 with Prof. Brandeis in ISSY to Greece on an 

 errand for the furtherance of archaeological 

 research ; afterward, with Ottfiied Miiller, 

 spent four years in Greece in historical and 

 archaeological studies, and began in 1864, 

 but carried on with great activity after 18*75, 

 the excavations at Olympia which have been 

 rewarded with the richest and most abundant 

 treasures of classic art. From 1844 to 1849 

 he was extraordinary professor at the Uni- 

 versity of Berlin and tutor to the crown 

 prince. In 1856 he was elected professor 

 at Gottingen, but returned to Berlin as pro- 

 fessor in 1868. His History of Greece is 

 rivaled in merit only by Grote's, and is its 

 fitting complement, supplying what Grote's 

 lacks as Grote's supplies what it lacks, and 

 is distinguished by the life it gives to the old 

 legends and its appreciation of the artistic 

 genius of the Greeks. He also published — 

 works of equal merit in their respective 

 fields — a book on the Acropolis of Athens 

 (1844) and an account of the Discovery of 

 Olympia (1882), besides many smaller works 

 and monographs. 



Plant Breeding. — In a recent copy of 

 Nature M. T. Masters has an interesting arti- 

 cle on Plant Breeding, from which the fol- 

 lowing extracts are taken : The natural pro- 

 cesses of variation in the plant world as con- 

 trolled by the art of the gardener are well 

 typified in the garden rose of to-day — quite 

 a different flower from those roses of our 

 forefathers, which have, with a few excep- 

 tions, totally disappeared. It is the same with 

 peas and potatoes and with most other plants 

 that are grown on a large scale. The two 

 methods made use of by gardeners for the 

 improvement of plants are selection and 

 cross-breeding, the latter, as far as results 

 are concerned, only a modification of selec- 

 tion. The natural capacity for variation of 

 the plant furnishes the basis on which the 

 breeder has to work, and this capacity varies 

 greatly in degree in different plants, so that 

 some are much more amenable and pliant 

 than others. The trial grounds of our great 

 seedsmen furnish object lessons of this kind 

 on a vast scale. The two processes are an- 

 tagonistic. On the one hand, everv care is 



