1879.] The Physical Properties of Liquid Acetylene. 209 



Potassium. 



0*065 grm. gave 



18-8 c.c. at0°C. + 760mm. 



mol. wt.— 



77-2 



0-083 



22-4 



33 



82-7 



0-077 



19-6 



53 



87-7 



0-075 



18-5 „ 



3) 



90-5 



0-077 



20-0 



33 



86-0 



0-070 



20-0 



33 



78-2 



0-077 



22-6 



33 



76.1 



0-087 



26-1 



33 



74-4 









652-8 





Mean molecular weight. 





81-6 





Sodium. 







0*043 grm. gave 



15-1 c.c. at0°C. + 760 mm..- 



mol. wt.— 



63-6 



0-067 



23-9 



33 



62-6 



0-047 



19-2 



33 



54-7 



0-040 



17-6 „ 



33 



50-7 



0-059 



28-6 



33 



46-0 



0-040 



20-4 



33 



43-8 



0-045 



23-36 



33 



43-0 



0-037 



20-2 



33 



40-9 



405-3 



Mean molecular weight 50'66 



Four pieces of potassium weighed in iron capsules and thrown into 

 water, gave 84*2 as a mean molecular weight, calculated from the 

 hydrogen evolved. Four pieces of sodium similarly treated, gave 49 "8 

 as a mean. The above experiments show that no great accuracy in 

 the determination of the vapour density of sodium and potassium can 

 be attained by this method of working when vessels of wrought iron 

 are employed. The results are, however, conclusive as regards the 

 normal character of their respective vapour densities. 



XVIII. " The Physical Properties of Liquid Acetylene." By 

 Gerhard Ansdell, F.C.S., Chemical Assistant to the Royal 

 Institution of Great Britain. Communicated by J. Dewar, 

 F.R.S., Professor of Chemistry, Royal Institution. Received 

 June 12, 1879. 



The hydrocarbon acetylene, being the only one of its numerous 

 class which can be formed synthetically by the direct union of its 



