A slag is said to be basic when it is composed of metallic oxides;: or, in other words, when the base of the slag is a metal the slag is said to be basic. Oxide of iron and oxide of calcium are true basic oxides, and form highly :basic slags.
A slag is said to be acidulous when it is composed of a mettalloid, such as silicon, phosphorus or sulphur, oxidized to silicic acid, phosphoric acid, or sulphuric acid, and these acids combine with a base forming silicates, phosphates or sulphates. When these compounds are present in a slag in a large degree it is said to be of a highly acid character.
โข ' When a metallic process is conducted in the presence of a highly: basic slag it is called a basic process, and when it is conducted in the presence of a highly acid slag it is called an acid .process.
The process by which the ancient Romans and Britons~ made their iron is known as the Catalan process. It was conducted: in aa open chamber, surrounded on all :sides and the bottom with a lining of charcoal dust. The fuel was used in this metal chamber admixed with the iron ore and metal. The slag present in this metal chamber, and, produced by this process, was principally composed of oxide of iron; hence the Catalan was and is a basic process.
The blast furnace is lined with stone or brick, both of which are highly acidulous, and, although limestone is used as a flux, owing to the silicious character of the ore and ash of fuel the slag is of an acid character, as will be seen by the following analysis:
Silicic acid, 58 Lime, . 23 Alumina, . 8 Magnesia, 2 Manganese, . Oxide of iron, 9 Hence the blast furnace process is an acid process. *In republishing the paper of Mr. Reese on this very important subject, this journal does not endorse the chemistry of the article.
Electric
Motor.--It has been proposed to build dams upon the Seine, so as to create a water power which could be transmitted, by Siemens or Gramme machines, to different parts of Paris, and used for drawing vehieles.--Chron. Industr.
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