It is a well-known fact that the managers of but few electrolytic plants grant technical visitors, and especially writers, access to their works, and that it has hitherto been extremely difficult or impossible, therefore, to secure accurate descriptions of certain American and European refining appliances, methods, and works. Воспроизведено в оригинальной авторской орфографии издания 1911 года (издательство "Chapman & Hall").