[Footnote 1:  Inverted by boiling with a 2.5 per cent. solution of
citric acid for ten minutes.]

Both the French and German governments are introducing it into their military dietaries, and in England several large contract orders cannot yet be filled, owing to insufficiency of supply, while a well-known cocoa manufacturing firm has taken up the preparation of kola chocolate upon a commercial scale.—­W.  Lascelles-Scott, in Jour.  Soc.  Arts.

* * * * *

CHAPIN WROUGHT IRON.

By W.H.  Searles, Chairman of the Committee, Civil Engineers’ Club of Cleveland, O.

Notwithstanding the wonderful development of our steel industries in the last decade, the improvements in the modes of manufacture, and the undoubted strength of the metal under certain circumstances, nevertheless we find that steel has not altogether met the requirements of engineers as a structural material.  Although its breaking strain and elastic limit are higher than those of wrought iron, the latter metal is frequently preferred and selected for tensile members, even when steel is used under compression in the same structure.  The Niagara cantilever bridge is a notable instance of this practice.  When steel is used in tension its working strains are not allowed to be over fifty per cent. above those adopted for wrought iron.

The reasons for the suspicion with which steel is regarded are well understood.  Not only is there a lack of uniformity in the product, but apparently the same steel will manifest very different results under slight provocation.  Steel is very sensitive, not only to slight changes in chemical composition, but also to mechanical treatment, such as straightening, bending, punching, planing, heating, etc.  Initial strains may be developed by any of these processes that would seriously affect the efficiency of the metal in service.

Among the steels, those that are softer are more serviceable and reliable than the harder ones, especially whereever shocks and concussions or rapidly alternating strains are to be endured.  In other words, the more nearly steel resembles good wrought iron, the more certain it is to render lasting service when used within appropriate limits of strain.  Indeed, a wrought iron of fine quality is better calculated to endure fatigue than any steel.  This is particularly noticeable in steam hammer pistons, propeller shafts, and railroad axles.  A better quality of wrought iron, therefore, has long been a desideratum, and it appears now that it has at last been found.