436 



KNO\A^LEDGE 



[March 17, 1882. 



tlioRe ]>iil)liiihr<l by ninrkio A Snim, under the direction of E. J. 

 PoynttT, H.A. — Uohkut Macphkhwin. 



[i;7l]- MiKCKi-LANHoi'M.— Till) Irontniciit of chnlk fornminifi'ni 

 difli'Di »<iiiipwlmt from tliiit of foniniinifi'rouN Hand. A very MitiH- 

 fnctiiry mcthiKl in lo boil n niiinll piocp of clinlk with rniixlic (KilnHh 

 in II tent tube until it wimmteii in lino powder. 'I'hiH in dhiiken np 

 in a lnr({e bottle full of wnter, tlie fornniinifeni nri' then He|iiiratod 

 by wpecilie gravity, the water Iwing poured off lifter HtJiiidinga Hhort 

 time, and a fresli iin|>ply added nn long as it cinneg away of a milky 

 tint. The deposit will eonniBt ehielly of foraminfern. and may be 

 mounted in balsnni. I liaro prepared ooveral Hlides of e)ui1k from 

 the North Downs, in Kent, by tliia method, which 1 have always 

 found to answer perfectly well.— C. Habkis. 



1 275] — Salt. — Tho objection to the use of salt can only bo ae- 

 counted for by some peculiarity of taste. It is certainly not 

 shared, ns far as I know, by any of our " high medical authorities." 

 By the use of salt the salivary glands, tho secretion from which 

 aids in the digestion of food, are stimulated. Its use is, of course, 

 not absolutely necessary; but that it is the most natural of all 

 condiments, and therefore the best, is made evident by tho fact 

 that saline matters are contained in all kinds of natural food. — 

 KoBEBT MAcrnEnsox. 



[275]— Salt. — Many object to salt on the idea that it is an 

 acquired tustc ; thoy say salt is not a natural part of man's food, 

 and so wo ought not to take it. They instance children, who always 

 splutter ont salt food when given them. It creates a false appetite, 

 and a craving for food even when the stomach is fidl. Also giving 

 rise to thirst, or a desire to drink. It increases the flow of gastric 

 juice and of saliva, for a time, tho same as any other bitter sub- 

 stance will. Some object to it on the ground of it being a mineral, 

 and say that our food contains all that is needed without it. I 

 know many vegetists who never take it from year to year, who 

 cook everything without it, and who even have it not in their 

 houses. — f. R. Alli.vson, L.R.C.P. 



[277] — LuMixou.-i Paixt.^ — This consists of calcium sulphide, 

 ground in oil. The light given by it is bluish. A 6-inch square 

 surface will show time by watch. Of course, the paint must have 

 been recently exposed to light. — Lkwi.s Arvxdel. 



[277] — Luminous Paint. — This is sulphite of calcium, made by 

 burning oyster shells in a closed vessel with sulphur.— Albert 

 Smith. 



[278] — Smell from Burning Gas. — Tho gas is imperfectly con- 

 sumed: The globes sometimes cause a rusli of air, through the hole 

 being too small, and then the gas is not consumed. — A. Ssiith. 



[282] — S.MELLINC Salts. — The use of smelling salts is only bene- 

 ficial in cases of fainting and nervous depression, and at times in 

 neuralgic headache. Women use them more fiequently than men 

 for the same reason that men use tobacco more frequently than 

 women, the force of custom in both cases being the ruling power. 

 — KoBERT JIacpiierso.v. 



[281] — Pkncil-point Protectors. — You can re-silver, using 

 cyanide of silver ; it is very poisonous. — A. Smith. 



[285]— Scientific Terms. — Collins & Sons publish an illustrated 

 Dictionary of Scientilic Terms, by W. Ito.ssitor (price 3s. Gd.) ; very 

 useful and compact. Anything not in Rossiter is easily found by 

 taking the Roots and consulting a Latin or (Jreek dictionary, as the 

 case may be. — G. B. 



[28G] — Electricity. — Get Spraguc's " Electricity," publislicd by 

 Spoil, Charing Cross. — A. Smith. 



[297] — Tobacco and Science. — TjTidall has shown that tho blue 

 of the sky and the blue of tho sea are caused by the breaking up of 

 the rays of light by infinitely small particles of solid matter. The 

 blue smoke rising from the glowing end of n cigar or pipe contains 

 very minute particles of carbon at a high teinperaturo. After the 

 smoke has been drawn into the mouth and expired, two changes 

 have taken place — the smoke is at a lower temperattii'e and laden 

 with moisture. It is also heavier. Perhaps there has been some 

 chemical change in addition. At any rate, we may safely say the 

 atoms of carbon have united into larger particles— just as coal- 

 smoke particles form smuts — and reflect light in a different 

 manner. The smoke issuing from the paper tube of a cigarette 

 contains tho two smokes — a small quantity of smoke at a high 

 tcmiKsrature drawn back from the glowing end. and a larger quan- 

 tity of cold smoke that has been in the smoker's mouth, which has 

 been rendered doi-ker and heavier. — W. D. B. 



PiioTocRAPiiic Bromide Solution.— Ammonia bromide, (!0 grains ; 

 liquid ammonia, 4 drachms; dis. water, 12 drachms. — A. Smith. 



[Letter 309]— Dur.vtion ok Life.— S. wants to know what I mean 

 by stating that it depends on ourselves whether we die at 35 or at 



70. It in thin, "All diaeaaon arc due to three condition!": — l*t, { 

 my parent's fault; 2nd, my neighbnar'H fault; 3rd, my own fault. 

 Int. If my parents tninsmit tome a tendency tu gout, coiiRumption, 1 

 or insanity, then the fault of ill-health belongs to them. If • | 

 person ilies before 20, it is the fault of hin parents, after that it ia 

 liis own fault. 2nd. If my neiglilxjur's drain rtins over, poisons mt 

 drinking water and I get typhoid fever, then he is to blame, 

 nnnther one comes lo my house whilst he is suffering from sma 

 po.x and gives it to me, then surely I am not to blame. 3rd. Thill 

 the largest class, and contains mo.st diseases, for by caro the I 

 dime}' to gout, Ac, can be rootefi ont from the system. Giv 

 many jiersons taking rich food and much of it, then bilious att 

 are to be looked for. If the rich food !« continued for n long ( 

 then expect gall stones and stones in tho bladder. Give alcohd 

 and we get chronic indigestion, rheumatism, &c. Give rich fo 

 and alcohol, and we get gont, apojilexy, heart, kidney, and Ut 

 disease. Give tobacco, expect sore throat, palpitation, slowing 

 heart's action, and in some few cancer of the lip. If fresh air I 

 neglected, then expect colds on the least exposure. If exercise 1 

 not taken, we expect constipation, piles, congestion of liver, 

 Now add up the action of lots of meat, plenty of drink and tobacc 

 and we shall get our people dying at 35 years. Take all in modd 

 ration, and an average constitution will last till nearly 70. But 1 

 abstaining from beer and tobacco and being spare with meat, I 

 taking plenty of exercise and fresh air and keeping the mind cab 

 we may go to fourscore or more. — T. R. Axlinm^v, I, lif'.I' 



^nsinns to Conrepontifnts. 



*^*All eommitnicafionit for the EJitor requiring rarly atlfntion thoutd rtaeh t 

 Offict on or before the SaturJai/ prtcedinf] the current istue of Kkowlbdoi, 

 inereating circictaiion of which compel* um to go to prett early in the teeek. 



Hints to CorrespOndrnts.— 1. Xo quention* atJcintj for tcicntific in/or 

 can ie answered through thepoft. 2. Lettert aent lo the ICditor for corre»pond«ni 

 cannot be fortcarded ; nor can the name/ or addreinei of corretpondentt be gicen i 

 anetcer to private inquiries. 3. iVo qiieriet or replies tarouring of tke nature i 

 advertifementH can Is inserted, 4. Letters^ queries, and replies are inserted, i 

 contrary to Eule 3, free of charge, o. Correspondents shouUi write on one 

 onltj of the paper, and put drawings on a separate leaj. 6. Each letter, \ 

 reply should hate a title, and in replying to letters or queries, r^er 

 nade to the number qf letter or query, the page on which it appears, and tie titie. 



t should \ 



A Reader and Subscriber to KNom,EDGE. The subject is I 

 considered in treatises on jAysiologj-. — Mathf.maticus. Math 

 matieal course at Dublin is excellent. — J. SI. You are not conted 

 with 2Jd. for 2d., but insist on 3d. or 25d. at the least. The pap 

 is excellent. — II. A. Bulley. You evidently misapprehend wh 

 science says on the subject. You carefully make a straw gia 

 and as carefully npset him. — Tyro. As to your first, ask us 

 easier one. As to tho other, to find how maeh a ton at earth^ 

 surface is attracted to the moon, multiply a ton by the square 

 3,960, divide by square of 238,818, then by 81, and you will get th 

 mass whose downward pressure at earth's surface is equal to attp 

 tion of a ton of matter (on earth) moonwards.- Xicholas MobgA 

 Pardon me, the phrenologist contends for something more than tb 

 difference of cranial form indicates a like difference of disposit 

 or of talent, or of form. .So !iii(r/i, many admit who arc 

 phrenologists. The JIallicolese skull compression cannot, howeva 

 afford much ground for argument cither way. — 1"eeli), or Jecl 

 or Yeela (??). Have never heard of Dr. Long's " Astronomy^ 

 For a beginner, should say Guillcmin's "The Heavens" (Bentley 

 would suit. — A. N. That frog cure is really too absurd, also to 

 cruel. — Cklt wants his theory discussed, that the builders of th 

 Great Pyramid heaped up earth all round tho Pyramid so i 

 form a slanting surface to the Pyramid level, as it rose layer 1 

 layer, and afterwards removed all that earth. He thinks — but do 

 not say why — that this would explain the slant passages. He as^E 

 if any one can offer a better theory. " In those days," 

 says, " engineering appliances were not likely to be able oth 

 wise to raise such great blocks of stone, and labour was pr 

 tically unlimited." It must have been, if the theory is eorrect.- 

 CiiARLES Horxer. It would be simply absurd to tell our reade 

 that the Great Gallery has been measured to within a hnndredt] 

 of an inch. No one who knows anything about measureme 

 would believe it of any gallery fifty yards or so long, still less ' 

 tho Pyramid (iailcry. You could make the length anything betv 

 1,870 and 1,890 in. according to the way you chose to measure, an 

 anything between 1,800 and 1,050, according to the length yo&l 

 choose to assign to the pyramid inch. These coincidences are mertl 

 tricks, though honestly meant enough, I have no doubt. Th4l 

 length of York Jlinster is quite as near the 1,000 millionth of i 

 sun's mean distance as the Pyramid's height ; so is the height cCf 

 Rouen Cathedral; but no one has yet started any craze about thediriap [ 



