As someone who loves to read more than anything else, I have long also been addicted to classic textbooks. Some of the most memorable moments of my student life involved walking into ghostly libraries looking like medieval castles and dusting off inches of dust collected on tomes which I regarded as treasures, volumes of great works that had not been checked out in 25 years and were languishing in anonymity, begging to be touched and read.
Sadly very few seem to bother about these anymore and regard them as outdated. I can bet that no modern undergraduate that I can meet has browsed Pauling's classic "The Nature of the Chemical Bond", a book that is regarded by many as one of the most influential works in chemistry of all time. In my opinion these students confuse outdated with poorly written. But many of the basics of chemistry don't change, and many of these old works provide crystal clear treatments of basics that are lacking in more modern books. As far as fundamentals go these books have stood the test of time and several are still in print, although some regrettably are not. A comment by Srini about Morrison & Boyd brought back fond memories of favourite classics...
Morrison & Boyd: I have already mentioned it before. Crystal clear treatments of mechanism with an especially outstanding chapter on electrophilic aromatic substitution. For organic chemistry, I have to admit that the new book by Clayden et al. is probably the single-best book on the subject I have seen, but the elegance of explanation in M & B is still hard to beat. I also remember the book by Roberts and Caserio also being pretty good. For what it's worth, the book which compresses the most number of insights in the fewest number of words is a slim volume by Peter Sykes whose clarity in explaining mechanistic concepts in short, crisp paragraphs is unprecedented.
The Great Linus Pauling: I first saw "The Nature of the Chemical Bond" as a freshman. While I then perceived it as boring and too detailed, it was only later that I recognized its monumental significance. Many famous scientists including Max Perutz and Francis Crick have learnt chemistry from it and Pauling's other book. The number of ground-breaking concepts that Pauling invented and put into this book is staggering. Especially check out the chapters on hybridization and partial ionic character of bonds. I have browsed all three editions, and the second one is probably the best-written, although the third edition is the most up-to-date and still in print. A measure of the book's significance in the history of science can be gained from the simple fact that after publication of the first edition the volume was cited no less than 16,000 times in the next 10 years. One constantly keeps on finding new papers in journals like Science and Nature that still cite it. Pauling's "The Nature..." did for modern chemistry what the Principia did for natural philosophy; it infused its subject with logic and tied together disparate threads to formulate a comprehensive and lasting science.
As if one work were not enough, Pauling also authored "General Chemistry". Again, it's a model of simplicity and clarity (note for instance how he explains the source of the difference in the three pKa values of phosphoric acid) although its emphasis on more descriptive chemistry makes it look a little quaint. The text is still widely read and in print as a Dover reprint edition; I have a copy on my shelf for a while now and recently saw one in the Barnes & Noble@GeorgiaTech.
Finally, "Introduction to Quantum Mechanics with Applications to Chemistry" co-authored with E Bright Wilson at Harvard was the first book to explain quantum mechanics to chemists. I will admit the book is not easy to read, but with effort one can find many gems in the first few chapters, especially the treatment of the hydrogen atom. Again, a Dover reprint is available and cheap.
With these three books, the prodigious Pauling secured his place in history not only as the greatest chemist of all time, but one of the most successful and greatest scientific writers of the century.
Glasstone: Samuel Glasstone was a remarkably prolific and versatile technical writer. It was in high-school that I came across a compendium of nuclear science that he had written, "Sourcebook on Atomic Energy". It is hands down the single-best example of technical science writing that I have come across, and wherever I have been since then, I have always had a copy on my bookshelf. The book is a model for comprehensive, all-inclusive writing that is clear as water from a virgin glacier. It also satisfies the difficult condition of being extremely valuable for both laymen and scientists. No praise for the book matches the praise that then AEC chairman and Nobel Laureate Glenn Seaborg penned in the foreword. Seaborg quipped that this was "technical writing at its very best" and that Glasstone was a man who had fortuitously come along at the right time to fulfill the needs of science and technology.
The range of Glasstone's writing is amazing; multi-volume works on physical chemistry and treatments of thermodynamics, electrochemistry, nuclear reactor engineering and even a sourcebook on space sciences. An exhaustively detailed and yet comprehensible book on the effects of nuclear weapons served as a standard declassified guide for years and is still in print. Although his PChem books are now really out-of-date, they still educated me in the basics when I first found them, and I learnt a lot from his book on thermodynamics. But again, nothing beats "Sourcebook on Atomic Energy" a book against which I think every other technical work should be measured.
"Valence" by Charles Coulson: Very few people in history have had the capacity to be both fine scientists and excellent writers. Charles's Coulson's book was the first book, even before Pauling and Wilson, to make quantum chemistry comprehensible to students. When it comes to pedagogical explanation it's hard to beat the British, and this is the finest example of that. I was fortunate to secure a copy at the famous Powell's bookstore in Portland, OR.
Classic books are like old wine. They should be cherished, preserved, and sampled one concept at a time.