There Are Many Kinds of Stamps : Page 24
Long since, the catalogues of the world have ceasedto call these "charity" stamps in favor of the more de-scriptive name, "semi-postal" stamps.
While many modern semi-postal stamps are franklyintended to raise funds for some stated purpose by in-cluding upon the stamp itself an extra charge, othersare not quite so obvious. The "charity" idea has oftenbeen hidden in devious manners. Thus Spain and Por-tugal, to mention two specific instances, have issuedlong sets of stamps which of themselves in no way indi-cate that they were intended to raise funds. These stampswere placed on very limited sale on certain designateddays and would not be good for postage on any daysother than the specified ones. The general public, ofcourse, would be largely unaware of this restricted useand few of the stamps would actually find their way intothe ordinary postal use. However, such stamps wereindeed postage stamps and were perfectly good forpostage purposes if used on the specified days. Hence,they received wide distribution among stamp collectorsand thus provided large sums of money without thenecessity of the Post Office performing any service. Suchincome is, of course, pure "velvet" and can amount to