The common rat poisons are Arsenic, Strychnine and Paris-green. These are put up by enterprising people under a multitude of suggestive names, without specifying the kind of poisons used, however, or even a warning of their being poisonous, as the law implicitly directs. There is, indeed, a great deal of criminal negligence in the way these poisons are put upon the market, as in some the proportion of poison is so great that it would kill an elephant--whereas it should be exactly graded to the rat's capacity. The proportion of arsenic in one very-much-advertised rat-poison now in use, as analyzed by Dr. Otto Grothe, a Brooklyn chemist, consists of 98.19 per cent. pure arsenic and 1.81 per cent. admixtures (coal, etc.). Would-be suicides and murderers have made use of these poisons extensively. Poisons in powdery form--such as arsenic and strychnine--are liable, very easily, indeed, to get mixed up with food, and have in that way been a powerful death-dealing agency. Their peculiar effect on the rats is to allow them to get over-doses, causing violent vomiting, followed by complete failure to kill or drive out. The Phosphoric Paste, the "Sure Pop" brand of which is very carefully manufactured by the present writer, is free from all of these objections, as it is in salve form and very hard to be accidentally mixed up with edibles of any kind. It is impossible for the rats to receive overdoses of it; and the phosphorus has the effect of burning and irritating them internally and forcing them to run for fresh air. Arsenic and strychnine rat-poisons are usually prepared in such heavy quantities that the rats prematurely die in the holes. On the other hand, the amount of actual poisonous matter in this "Sure Pop" Phosphoric Paste has been exactly proportioned to the rat's system, making the amount of poison very slight. There is no secret at all in the compounding of this preparation, but it requires much experience and study of the rat's nature, preferences and habits to make it so that it will work with proper effect. The utmost daintiness is also required in the handling of all its ingredients. We have practically shown on page 40 how the smell of phosphorus is the most powerful of attractions known to the rat, and how it will operate when everything else fails. III.--DOGS, CATS AND FERRETS.