_Registration._--All classes of matter may be registered to places in Canada, the United States and Postal Union Countries, and the sender may entitle himself to an acknowledgement of delivery from the party addressed by the payment of a fee of 5 cents in addition to the registration fee. (A) _Commercial Papers_, (B) _Books and_ (C) _Samples, for Postal Union Countries_. "Commercial papers" comprise all papers or documents, written or drawn, wholly or partly by hand, (except letters or communications in the nature of letters, or other documents having the character of an actual and personal correspondence), documents of legal procedure, Deeds drawn up by public functionaries, copies of, or extracts from Deeds under private seal, Way-Bills, Bills of Lading, Invoices and other documents of a mercantile character, documents of Insurance and other public companies, all kinds of manuscript music, the manuscript of books and other literary works, and other papers of a similar description. "Printed Papers" include periodical works, books, stitched or bound, sheets of printed music, visiting cards, address cards, proofs of printing with or without the manuscript relating thereto, engravings, photographs, when not on glass or in frames containing glass, drawings, plans, maps, catalogues, prospectuses, announcements and notices of various kinds, printed, engraved, lithographed, printed circulars. (A) Limits of weight and size: 5 lbs. for the United Kingdom, and 4 lbs. for other countries, 18 inches in length and 12 inches in width or depth. (B) 5 lbs. for the United Kingdom, and 4 lbs. to other countries, 2 feet long and 1 foot wide or deep. (C) United Kingdom, 5 lbs. in weight, 2 feet in length by 1 foot in breadth or depth. (D) Limits of weight to Austria-Hungary, Belgium, Egypt, France, Hawaii, Italy, Portugal, Roumania and Switzerland, is 12 ozs., limit of size 1 foot in length by 8 inches in width and 4 inches in depth. If in form of a roll it may be 12 inches in length and 6 inches in diameter. The limit of weight to other Postal Union Countries is 8 ozs., limit of size same as to Austria-Hungary, &c., &c. _Matter Which Cannot be Forwarded Through the Post._--Liquids, Oils, etc., not properly put up. Explosive Substances and other matter likely to entail risk or injury to the ordinary contents of the mail, cannot be sent by post. Letters containing Gold or Silver Money, Jewels, or precious articles, or anything liable to Customs duties, cannot be forwarded by Post to any of the Postal Union Countries except the United States.