Polytechnic Association Proceedings. §79 



effervescrn'g citrate of magnesia. 

 A correspondent of The Chemical JVeivs asserts that the com- 

 pound sold in England, under the name of " granular effervescing 

 citrate of magnesia," contains neither magnesia nor citric acid; 

 another correspondent states that it is nothing more than citro- 

 tartrate of soda, with the addition of sugar and four or five per- 

 cent of sulphate of magnesia. 



OOLOGY. 



Dr. Blasius has given, in KolUJceft'^s Zeitschrift, part third, an 

 account of his microscopic examination of birds' eggs, to ascertain 

 whether they present sufiicient distinguishing characteristics to 

 separate the larger groups of birds; he reports that the minute 

 differences revealed by the microscope are neither constant nor 

 trustworthy, and are, therefore, of no importance in systematic 

 ornithology. 



STRUCTURE OF THE LIVER. 



Prof. Herring, from a study of the minute structure of the liver 

 of a rabbit, as well as many other mammals, concludes that the bile 

 passes to the periphery of the lobule in channels which lie between, 

 and have their walls formed by the liver cells, and which commu- 

 nicate with the interlobular branches of the hepatic duct. The 

 new view is accepted by Eberth and other prominent histologists. 



HEAT OF FUSION. 



The melting point of metals and fusible silicates is lower than 

 usually stated. Wedgewood's pyrometer and other similar meas- 

 uring instruments have been found to be quite unreliable for high 

 temperatures. Herr C. Sching, has shown by the application of 

 the thermo-electric pyrometer, that the temperature of a glass fur- 

 nace in operation is only from I.IOO'' to 1.250" Centigrade. Crys- 

 tal glass becomes completely liquid at 929" C, and is worked at 

 833". A Bohemian glass tube softens at 769° and becomes liquid 

 at 1,052*^ C. Pure limestone loses its carbonic acid by heating 

 for several hours at 617'' to 675^*, C. The gas can be driven off 

 more rapidly by increasing the temperature. 



RIVER IMPROVEMENT. 



An officer of the United States Coast Survey, has lately surveyed 

 the head waters of the Minnesota river, with a view of turninof into 

 it the outlets of many lakes, which now discharge into the Bois de 

 Sioux, which flows north, and is the principal branch of the Red 



