The sides of the ladder are the spectra furnished by the incandescent carbons of the lamp, and the cross pieces are the spectrum of the electric arc filling the space between the carbons.
"A Text-Book of Astronomy"
George C. Comstock
Explosions of kerosene are caused by the presence of the lighter hydro-carbons, as naphtha, etc.
"An Introduction to Chemical Science"
R.P. Williams
Notice that, in going down the list, the proportion of C to H becomes much greater, and the lower compounds are the heavy hydro-carbons.
"An Introduction to Chemical Science"
R.P. Williams