My initial reaction on receiving this book was "Bloody hell is it big enough!?" At 1024 pages you're certainly getting a lot of information for your buck.
Eastlake (1793-1865) was a former president of the British Royal Academy, director of the National Gallery, and in his day an major expert on painting techniques. Do note the book was first published in 1847, hence the writing style can be somewhat turbid. Perseverance pays with there being more information in here than you can shake a stick at.
My comment about caution is based upon recent studies of old master paintings. The old masters would typically have a team of apprentices working alongside them, mixing paint, painting parts of the painting that the master was probably too bored to bother with (as well as good training for the apprentice) etc. The Master/Apprentice setup allowed for a continuous stream of knowledge being passed along the generations. However as oil paint technology advanced, in particular the ability to buy premixed paints off the shelf, the painter no longer needed a team of apprentices. He could pretty much get by on his own. Hence there was no longer anyone for the painter to pass on his knowledge to. This resulted in a considerable amount of technical knowledge being lost. (A good example is the recent theory promulgated by David Hockney that the old masters were able to paint such realistic paintings as they used rudimentary projection techniques to place a guide image on the canvas, overwhich they painted. No one knows if he is right or wrong).
From the 1800's on, technical experts such as Eastlake and Max Doerner ("The Materials of the Artist") began to impart their wisdom on how the old master paintings were created. But the techniques thay had available were very rudimentary, more often than not being a case of the expert trying to reproduce a certain style and looking at the painting surface close up. The experts proferred their theories and techniques, often with much aplomb leaving no room for doubt. Unfortunately they were often quite off the mark - they could emulate a style somewhat but never 100%. There are too many variables involved even for a discerning eye. It has only been with recent advances in scientific analysis, chemical and visual, that a truer understanding of the old master technique is finally being determined. Van Wettering's excellent "Rembrandt - the painter at work" book details the findings of extensive research carried out on a number of paintings considered to have been painted by Rembrandt. The book is 340 pages, and they still haven't got all the answers. But what they have done is to throw in to doubt the theories and techniques of the 19th/20th C experts.
There is a welter of information in this book, but if you are trying to perfectly replicate a certain old master painterly technique, and failing to do so, then be warned the experts might not be such experts afterall.
All said and done, I do recommend this book for the wealth of information it contains. Numerous recipes for mediums, varnishes etc. along with many techniques that it lends itself to study in its own right. Dover books have once again provided an excellent product at an excellent price.