This book compiles not only comprehensive experimental results on the rare earth metals in metallurgy, but also some important industrial applications. China is rich in rare earth metal resources, and alkaline earth elements are more and more used in metallurgy in the last few decades, so a lot of research has been made on physico-chemical characteristics of these elements in metallic melts. The last four paragraphs of the book introduce physico-chemical characteristics of other important elements in metallurgy. Readers will find many data concerning the above field in this book. A lot of data of them have been obtained by the author and his colleagues through highly precisive analysers such as an auto-radiograph, etc. In view of the fact that some of the studies have not been published in English before or have not appeared in any publications, some topics are discussed in details for the convenience of readers.