Silico-acetylene, (Si₂H₂)_n

Silico-acetylene, (Si₂H₂)_n, was prepared by Bradley by decomposing calcium silicide with hydrochloric acid:

CaSi₂ + 2HCl = CaCl₂ + Si₂H₂.

It is a yellow crystalline substance, showing no resemblance to acetylene, and is undoubtedly polymerised.

The following table shows the boiling- and melting-points of the three hydrides of silicon, together with those of the corresponding hydrocarbons. The difference in boiling-point between ethane and silico-ethane is particularly noteworthy.

	CH4	SiH4	C2H6	Si2H6	C2H2	(Si2H2)n
B.P. ° C.	-164	-115	-93	+52	sublimation temperature	solid
M.P. ° C.	-184	cir. -200	-123	-138	-85	M.P. unknown