Solve times for this jigsaw puzzle
The first "friction match" was invented by English chemist John Walker in 1827. Early work had been done by Robert Boyle in the 1680s with phosphorus and sulfur, but his efforts had not produced useful results. Walker discovered a mixture of antimony sulfide, potassium chlorate, gum, and starch could be ignited by striking against any rough surface.
Share this Jigsaw Puzzle
Sat Roqubrun CanoeFri Carpet Black GoldThu Brugmansia Pink BeautyWed Peruvian Hairless DogTue Horse Leg WrapsMon Ice Cream ConeSun Urn Gate PostsMore Previous Puzzles