520 M. Mendelejeff on the Expansion of Liquids. 



lime and magnesia salts do not require less solution of soap, as 

 stated by Dugald Campbell*. Liebig states in a note toWilson's 

 paper, that a determination made by Fink of the water of the 

 chemical laboratory corresponded to 16 degrees hardness. A 

 determination of the quantity of alkaline earths contained in a 

 litre of water, gave 0*114 grin, lime and 0-035 grm. magnesia, 

 which together correspond to 16 degrees of hardness. 



Mendelejeff has investigated the expansion of liquids when 

 heated above their boiling-point f. These experiments were 

 made upon alcohol, ether, and water, and were effected by en- 

 closing these liquids in glass tubes of about 300 millims. in 

 length, 4 millims. internal diameter, and about 2 millims. thick 

 in the glass. To free the liquid from air, some of the liquid was 

 boiled in them, and they were then sealed. The upper part of 

 the tube was divided into millimetres. 



The tubes were heated by placing them vertically in a wide 

 glass tube, and passing a current of the vapour of absolute 

 alcohol, water, amylic alcohol, or oil of turpentine rapidly 

 through the tube. The temperature was indicated by means of 

 a thermometer placed along side the sealed tube. The obser- 

 vations were made by means of a cathetometer, and were read 

 off when the height of the liquid in the tube and the correspond- 

 ing temperature were constant. The vapours, after being used 

 for heating, passed into a condensing apparatus. The experi- 

 ments were made with all possible precautions, the details of 

 which are described in the paper. 



A very remarkable result was obtained from these experiments ; 

 that is, that the empirical formulas of Kopp, wbicli express the 

 expansibility of ether, alcohol, and water up to the boiling-point, 

 may also be applied with the same accuracy to the expansibility 

 at far higher temperatures. 



Mendelejeff also found that this held good for benzole and 

 chloride of silicon, and concludes that the agreement of the cal- 

 culated numbers with those obtained by experiment is so close 

 that it will probably prevail with all liquids. 



It further follows from these experiments that the expansion 

 of liquids above the boiling-point obeys the same laws as under 

 the boiling-point, — that the coefficient of expansion increases con- 

 tinually and gradually with diminution of the cohesion of the 

 liquid, that is, with an increase of temperature. With some 

 liquids it is as much as that of gas at a certain temperature ; for 

 example, for ether at 133°. The coefficient of expansion of ether 

 amounts to 0*0054 at the temperature of its absolute boiling- 



* Phil. Mag. vol. xxxvii. p. 1/1. 

 t Liebig's Annalen, July 1861, 



