Dark material on floor tiles

[Lee J]

Looking at this floor with these not so great photos, would anyone take a guess at what the dark substance is covering the tiles? I wondered if it's the mastic they used to use which contained asbestos, or a general construction bonding that once stuck down a carpet or tiles?

Thanks

Lee.

 

[foxhole]

Just adhesive .

 

[JP_]

yeah, my guess is there was a rug of some sort stuck down there.

 

[Lee J]

Thank you for your help