Wiktionary
sparkless
a. without a spark
Usage examples of "sparkless".
She looked away, toward the fire that had burned down to sparkless ashes.
It may be asserted without the slightest fear of contradiction that there are at least fifty engineering firms in this country who could send forth a road locomotive very nearly noiseless, very nearly smokeless, certainly sparkless, capable of running up and down hill on our smooth and capital roads, perfectly under control, not in the least alarming to horses, and able to draw two or more trucks or passenger cars round all their devious windings at a speed at least equal to that of a moderate trot--say eight miles an hour.
The weave of the flames crawled upright and held, sparkless and steady and hot.