1.   High up in the sky was a protective layer of gas that screened out dangerous ultraviolet rays from the sun.

2.   Lifting the lid she flung aside the protective layers of tissue-paper.

3.   They replace essential moisture whilst forming a protective layer to hold it in.

4.   Sulphide may also destroy the disulphide bridges in mucus, in turn leading to a breakdown of the protective layer of the epithelium.

5.   That was until Norman Tebbit spotted what he believed was the biggest chance of holing the impenetrable protective layer around the bill.

6.   A virulent bacterium is able to produce anthrax toxin proteins and cover itself with a protective layer called a capsule.

7.   A.On the contrary, it is a thin waterproof protective layer, called a patina, that forms when copper is exposed to air.

8.   After they are stained, the doors are coated with a clear protective layer that helps hold the finish in place.

9.   But besides adding a nice, thick protective layer, there are also those countless sea critters, rich in calcium.