182 ANNUAL OF SCIENTIFIC DISCOVERY. 



For every gram taken there are disengaged, 



1 equivalent of amorphous boron in com- 

 bining with oxygen disengages 158,600 heat units. 14,420 heat units. 



1 equivalent of amorphous boron in com- 

 bining with chlorine disengages. .. 104,000 " 9,455 " 



1 equivalent of chloride of boron acting on 

 140 times its weight of water dis- 

 engages 79,200 " 7,200 " 



1 equivalent of amorphous silicon in com- 

 bining with oxygen disengages 109,620 " 7,830 " 



1 equivalent of amorphous silicon in com- 

 bining with chlorine disengages. .. 78,820 " 5,630 " 



1 equivalent of chloride of silicon acting 

 on 140 times its weight of water 

 disengages 40,820 " 2,915 " 



1 equivalent of amorphous silicon in be- 

 ing converted into the crystallized 

 variety disengages 4, 060 " 290 " 



" Hence it appears that, weight for weight, the calorific power 

 of carbon is less than that of boron, and that of silicon is less than 

 that of carbon when the carbon is oxidized to carbonic acid. If, 

 however, we compare equivalent weights, we find that an equiva- 

 lent of silicon gives out twice as much heat as an equivalent of 

 carbon, the amount of oxygen entering into combination being 

 the same in both cases. Moreover, when the carbon is simply 

 converted into carbonic oxide, as is the case in many metallurgical 

 operations, it gives off only about one-third as much heat as the 

 same weight of silicon in passing to the state of silica." 



The authors further speak of the importance of using iron con- 

 taining a considerable amount of silicon in the Bessemer process, 

 alluding also to the fact that the product of the combustion of car- 

 bon being gaseous, carries off heat from the converter, while the 

 silica formed remaining in solid state, the heat evolved in its pro- 

 duction is all utilized in maintaining the temperature of the bath. 



ALIZARINE. 



In spite of the many investigations of madder which have been 

 made, chemists are still in doubt as to the nature of many of its 

 constituents. Some attribute its coloring powers to the presence 

 of at least two substances, alizarine and purpurine, while 

 others say that only one of these produces the true madder colors. 



Alizarine was discovered and obtained from madder as a ci^s- 

 talline sublimate by Robiquet and Colin in 1831 ; but little impor- 

 tance attached to this discovery until Schunck, in 1848, showed 

 that all the finest madder colors contain only alizarine combined 

 with bases and fatty acids. The second coloring matter, termed 

 purpurine, was discovered by Persoz. It contributes to the full 

 and fiery red color in ordinary madder dyeing, but dyes a bad 

 purple, alizarine being essential to the latter. Purpurine disap- 

 pears during the purifying processes of soaping, etc., being far 

 less stable than alizarine. 



