Iron content of cow's milk

Iron content of cow's milk

534 CURRENT TOPICS. gramme of radium in equilibrium with its disintegration products to radium C was produced. This observed rate of production of h...

61KB Sizes 4 Downloads 99 Views

534

CURRENT TOPICS.

gramme of radium in equilibrium with its disintegration products to radium C was produced. This observed rate of production of helium closely agrees with the rate calculated from the counting experiments of Rutherford and Geiger (158 cub. mm. per year), thus proving that the ~ particle during its flight consists of a helium atom carrying two unit positive charges and that helium itself is monatomic. The agreement of the observed and calculated values is independent of the purity of the Ra-standard employed, as the same standard has been used in both measurements. Determinations of the amount of helium produced by the disintegration of a known quantity of radium emanation were also made, and found to agree with theory. The production of helium by polonium and from a preparation containing radio-lead was also observed.

Economic Working of S t e a m Boilers. C . W . JORDAN. (Mech. Eng., xxviii, 626.)---This paper refers to the difficulties connected with the regulation of combustion, and on the point of excess of air admitted to the furnace it is said that the ordinary water column draught-gauge gives indications of two causes of movement, via: ( I ) the pressure necessary to produce the desired velocity of air flowing through the grate, and (2) the pressure necessary to secure the flow of the fuel gases through the flues, etc., the one beihg dependent upon variable and the other upon constant conditions. A means is proposed of measuring the second one alone by the, use of a differential water column. The regulation of the feed water has been much neglected, and an auto-electric apparatus ; proposed for the purpose of controlling the feed; this apparatus is described and illustrated. It is dependent upon a float, the rod of which carries an iron bar forming the armature of an electromagnet. When this armature is brought by the water level into the magnetic field it is held so as to close the circuit of an electromagnet operating the field valve. The first magnet is cut out of circuit by the rising of the float, and the feed valve closes. Other details conducive to economical working are also discussed. I r o n Content of Cow's Milk. F. EDELSTEIN and F. V. CSONKA.

(Biochem. Zeits., xxxviii, I 4 . ) - - T h e figures previously given for the iron content of cow's milk range from I to t5 m~m. of iron per litre. It is now found that if the milk be drawn into glass vessels the iron content is o.4 to 0. 7 mgm. per litre, or from onethird to one-half that of human milk. In ordinary mixed dairy milk and in purchased milk the iron content was higher, o. 7 to 1.5 mgm., and less constant.

PRISS ,

~

LIPPINCOTT

Or COMP/

PHILADRLPHIA