CHAPTER XXXIII

.

LIQUID AIR.

Liquefaction of Gases by Northmore--1805, Faraday--1823, Bussy--1824, Thilorier--1834, and others. Liquefaction of Oxygen, Nitrogen and Air, by Pictet and Cailletet in 1877. Self-Intensification of Cold by Siemens in 1857, and Windhausen in 1870. Operations of Dewar, Wroblewski, and Olszewski. Self-Intensifying Processes of Solvay, Tripler, Lindé, Hampson, and Ostergren and Berger. Liquid Air Experiments and Uses.

## CHAPTER XXXIV .

MINOR INVENTIONS,

AND

Patents of Principal Countries of the World.

## CHAPTER XXXV .

EPILOGUE.

##