572 



SCIENCE 



[N. S. Vol. XXX. No. 773 



and half the yellow. The violet screen absorbs 

 strongly from about 33 to TO, that is, the 

 orange and the yellow. The sodium line at 

 50 is therefore absorbed by both screens. Thus 

 in the presence of sodium the red, green and 

 blue colors imparted to the Bunsen flame by 

 certain elements and compounds may be 

 readily detected by means of the screens. Cer- 

 tain colors transmitted by one screen are ab- 

 sorbed by the screens together. 



The strontium and the lithium flames ap- 

 pear deep red through the violet screen but 

 give no color through the blue screen. Barium 

 and boron give a vivid green through the blue 

 screen, and only a faint green through the 

 violet screen. Volatile calcium salts impart a 

 strong greenish-yellow color to the flame as 

 seen through the blue screen, but through the 

 violet screen the color appears a pale red. 

 Through the combined screens the flame has a 

 tinge of green. The color flashes out only at 

 the moment when the salt is becoming incan- 

 descent. Potassium gives through the blue 

 screen an intense blue-violet color; through 

 the violet screen the outside of Bunsen flame 

 is violet and the inside violet-red; through 

 both screens the flame appears as through the 

 violet screen, but less bright, and with red 

 predominating. These colors are very charac- 

 teristic. The copper chloride flame appears 

 bright blue fringed with green through the 

 violet screen, brilliant green through the blue 

 screen, and a paler green through both screens. 

 The flame color of phosphoric acid is green 

 through the blue screen, light rose color 

 (violet-red) through the violet screen and pale 

 green through both screens. 



In getting these flame reactions from non- 

 volatile compounds it is, of course, necessary 

 to use some flux or acid that will produce a 

 volatile compound of the element sought. A 

 silicate containing potassium may be powdered, 

 and decomposed in a sodium carbonate bead 

 on a platinum wire. The resulting potassium 

 carbonate is volatile. The phosphate minerals 

 apatite, lazulite and waveUite give the phos- 

 phoric acid reaction readily if powdered, taken 

 up on a moistened loop of platinum wire, 

 heated and then treated with concentrated 



sulphuric acid and again heated. The reac- 

 tion is transient. 



A screen 3X5 inches consisting of three 

 colored strips, one blue, one violet and one 

 blue over violet, suitable for general laboratory 

 use, has been made for the writer by Mr. G. 

 M. Flint, Cambridge, Mass., price 20 cents. 



Such a screen is conveniently handled and 

 is so delicate a means of identifying the ele- 

 ments usually sought by means of the spectro- 

 scope that its use greatly facilitates the work 

 of laboratory instruction in qualitative an- 

 alysis and mineralogy. 



In case lithium light free from sodium light 

 is wanted for use in optical mineralogy the 

 violet screen is a very serviceable filter. 



H. E. Meewin 



MiNEEAXOQICAL LABOEATOKT, 



Habvaed University, 

 August, 1909 



THE SCOMBROID FISHES 



In a recent paper " On the Anatomy and 

 Classification of the Scombroid Pishes " ' C. 

 Tate Began proposes to remove the family 

 Carangidse (with other families of more or 

 less possible scombroid affinities) from its 

 time-honored position among the scombroid 

 fishes, and place it among the percoids. 



This comes somewhat as a shock to many 

 ichthyologists, who, while having doubts as to 

 many of the so-called scombroids, have believed 

 the family Carangidse to be unquestionably a 

 scombroid family. Mr. Began writes of the 

 family Carangidee as follows: 



The more generalized members of this family 

 (Seriola, Naucrates) have the anatomical char- 

 acters of the Serranida;, there being nothing in 

 the structure of the cranium, vertebral column or 

 pectoral arch to differentiate them from the latter, 

 whilst genera like Scombrops and Pomatomus 

 (Temnodon) connect the two families. In the 

 Carangidae the caudal peduncle is more slender, 

 the caudal fin more widely forked, and the hy- 

 pural embraced to a greater extent by the bases 

 of the caudal flnrays than in the Serranidse, but 

 the close relationship of the two families is evi- 

 dent. 



' Ann. and Mag. 'Nat. Hist., Ser. 8, Vol. III., 

 January, 1909. 



