1903. 



on Low Temperature Investigations. 



423 



nearly as great a coefficient as paraffin, which is one of the most 

 expansive solids. 



It will be possible by cooling the moulds with liquid air during 

 the process of hydraulic compression, to produce cylindrical blocks 

 of solid bodies of lower melting-points, like alcohol, ether, nitrous 

 oxide, ammonia, chlorine, etc., and to ascertain their coefficients of 

 expansion in the solid state between the individual melting-points and 

 the boiling-point of liquid air. 



This method, which works well with liquid oxygen or air, fails 

 with liquid hydrogen, as the density of the liquid is too small to 

 give accurate values. For temperatures about 20° absolute, recourse 

 must be had to measurements of the coefficient of linear expansion, 

 and such observations at present could only be applied with any 

 accuracy to metallic bodies and alloys. 



Table I. 



Sulphate of alumiiiium (18)^ . 

 Biborate of soda (10) . 

 Chloride of calcium (6) 

 Chloride of magnesium (6) 



Potash alum (24) 



Chrome alum (24), large crystal . 



Carbonate of soda (10). 

 Phosphate of soda (12) 

 Hyposulphate of soda (5) . 

 Ferrycyanide of potassium (3) 

 Ferricvanide of potassium 

 Nitro-prusside of sodium (4) . 

 Chloride of ammonium, sample i. 

 „ „ sample 11. 



Oxalic acid (2) 



Oxalate of methyl 



Paraffin 



Naphthalin 



Chloral hydrate 



Urea 



Iodoform 



Iodine 



Sulphur 



Mercury 



Sodium 



Graphite (Cumberland) . . . 



Density 

 at -188°. 



•7194 

 •7284 

 •7187 

 ■6039 

 •6414 

 •8335 

 7842 

 4926 

 5446 

 7635 



8944 



7196 



5757 



5809 



7024 



5278 



9770 



2355 



9744 



3617 



4459 



8943 5 



0989 



382 



0066 



1302 



The figures ( ) refer to the number of molecules of wat«r of crystallisation. 2 At — 38*85°. 



Vol. XVII. (No. 97.) 



2 F 



