8 



♦ KNOWLEDGE • 



[JUXE 2, 



precise nature of the poison were known. We shall con- 

 sider cases of both kinds. But first, as 



Prevestiox 

 is better than cure, we may ninind the reader that every 

 substance, whether medicinal or otherwise — every drug or 

 rhemical which has poisonous ijualities — should be not only 

 properly labi'lled, but carefully kept out of harm's way, 

 and where there are children, shoiild bo kept under lock 

 and key. Better take precautions which seem unnecessary, 

 thaji run risks which may be avoided. If people would 

 treat a bottle of poison as they would (or rather as they 

 s/ioiihl) treat a loaded fire-arm, we should less often hear of 

 accidents about which, after they have taken place, the 

 person who has really caused it can only say, " I never 

 thought it could have happened." 



Arsenic. 



Arsenic has very little taste in the form in whieh it is 

 usually known in commerce — viz., as white arsenic or 

 arsenious acid, the white o.\ide of arsenic. For this reason, 

 it is often used for criminal purposes. But fortunately, if 

 it can be given easily, it can be detected as readily in the 

 l>ody, not only when present in very minute quantities, but 

 after many weeks and even months have elapsed from the 

 time when the body was buried. 



The first symptoms noticed after arsenic has been 

 swallowed are sickness and faintness, following generally 

 within half-an-hour after the poison has been taken, but 

 often much sooner. Then follow violent and spasmodic 

 pains in the bowels (increased by pressure), attended by a 

 ■burning feeling, dryness, heat and constriction of the mouth 

 and throat, increased How of saliva, and an unquenchable 

 thirst, itching of the face and neck, and palpitation of the 

 heart, with full, hard, and freiiuent pulse. Vomiting and 

 purging follow. Sometimes the skin is burning hot, at 

 others icy cold and covered with clammy perspiration. The 

 pulse sinks, becoming irregular and feeble. Then, if the 

 poison has been given in sufficient quantity, convulsions 

 *.-ome, and before long death cnsue.s. In certain rare in- 

 stances the symptoms above described are scarcely observ- 

 able, yet within a few hours the patient sinks ; in such 

 cases the presence of arsenic is indicated by a lethargic 

 sleep. In cases of slow poisoning by arsenic (which, how- 

 ever, do not belong properly to our subject, since in their 

 cast; the physician only can be of service) there is often no 

 recognisable symptom, no inflammation, no fever, constipa- 

 tion, or vomiting, but langour, weariness, and disgust for 

 food, followed by torpidity of the nobler organs, especially 

 the lungs — death coming as certainly, though not so 

 swiftly, as when a single poisonous dose has been taken. 



The best home remedy for arsenical poisoning is a 

 mustard emetic, but if sulphate of zinc can be oV)tained, 

 an emetic formed of from ten to twenty grains in about a 

 quarter of a tumbler of water, is better. For a mustard 

 emetic, take a dessert-spoonful of flour of mustard in a. 

 teacupful of warm (not hot) water. Large quantities of 

 milk or warm water, or, better still, linseed-tea or barley- 

 water, should l>e taken, to promotf; vomiting. Tickling 

 the back of the throat with a feather, or with the fore- 

 finger (if the patient has lieen accustomed to that way 

 of producing vomiting) may be resorted to with advantage. 

 Tlie patient should note, in all cases where the stomach 

 is to Ix; cleared of its contents, that, while much is 

 rejected after the throat has lieen tickled, it is well 

 after a while to wait for the sort of after - throe 

 which comes without sucli tickling, and seems to carry 

 away a portion of the stomach's contents which is retained 

 so long as the tickling is continued. It is better, however, 



to encourage vomiting rather by swallowing large quan- 

 tities of the warm liquids above-named than by irritating 

 the back of the throat. 



After the stomach has been cleared of its contents by 

 the use of emetics, itc, lime-water, or chalk dissolved in 

 water, should be swallowed in large quantities. Or, if none 

 is at hand, mix a pound of soap in two quarts of water, 

 and take a teacupful every five or si.x minutes. Failing 

 either of these, powdered charcoal, if at hand, may be 

 taken with advantage. It will be well for the patient, 

 however, if, before this stage of the treatment, a doctor is 

 at hand to take the case in charge. The after treatment 

 requires all the doctor's care in serious cases ; for the 

 above remedies are not, properly speaking, antidotes. 



THE AMATEUR ELECTRICIAN. 



OUR next task is to fix the inductor, A-c. To do this, 

 take a piece of brass plate a quarter of an inch 

 thick, twelve inches long, and shaped according to the 

 dimensions given in Fig. 7, which is a plan of the plate. 



Fig. 7. 



minus the parts which are to be fixed to it. It is repre- 

 sented in section by A B in Fig. 8. The lower pole-piece, 

 E F (C, Fig. 6, Jlay r!G), is to be screwed on say at C C C, 

 the heads of the screws being well sunk. P P' are two 

 brass standards, or pillars, about two inches high, to sup- 

 port the steel screws S S', which form the centres upoa 

 which the armature will revolve. These standards should 

 be ^•ery strong and firmly fixed*. They should be half an 

 inch thick, and shaped (in a vertical plane at right angles 

 to the axis), according to Fig. 9. This will tend to con- 

 siderably increase the rigidity and durability of the 

 machine. The centre-screws should, of cour.se, be fixed by 

 means of check-nuts on each side of the standards. 



When all is done, the plate, AB, must be firmly screwed 

 at available places (Fig. 8, G) to a .stout wooden base, of 

 which, however, more will be said when speaking of the 

 motive power next week. We have advised the use of 

 centres, as opposed to bearings, to obtain the best results 

 with the least expenditure of force, and because, further- 



G 



1^-=^ 



more, of the small weight which luis to revolve. Where, 

 however, a larger armature is used, or if even with the one 

 described, a high velocity is attempted, bearings should be 

 adopted ; otherwise, the wear and tear would be very great, 

 and we should soon spoil our machine. 



As regards the commutator (Fig. 5, May 20), the one 

 we are adopting is constructed on a principle which in- 



• It would be better, where it is poBsible, to have the plate and 

 standards cast in one piece, the standards being 9 in. apart. 



