A Guide To The Scientific Knowledge Of Things Familiar Part 76

A. The cowl of the capu'chin is _fastened to a piece of cat-gut_. When the weather is _wet_, the moisture _swells the cat-gut_ and it is _shortened_, by which means the _cowl is pulled up_; but in _dry_ weather, the _string is loosened_, and the cowl falls down.

Q. _In another weather toy, the MAN comes out in WET weather, and the LADY in FINE:--Why is this?_

A. The two figures are attached to a piece of _cat-gut_ in such a manner, that when the _cat-gut is shortened by moisture_, it pulls the _man out_; but when it is _loose_, the woman _falls out by her own weight_.

Q. _Why are WET STOCKINGS DIFFICULT to PULL ON?_

A. The moisture (by penetrating the threads of the stockings) causes them to _shrink in size_.

Q. _What is the MOST RAINY spot in ENGLAND?_

A. Keswick (in c.u.mberland); and then Kendal (a market town in Westmoreland).

(In Keswick, about 63 inches of rain fall in a year. In Kendal, 58; Manchester, 38; Liverpool, 34; Dublin and Cambridge, 25; Lincoln, 24; London, 21; and in Paris, only 18.)

Q. _In which PART of the DAY does the MOST RAIN fall?_

A. More rain falls by _night_ than by day; because the cold night _condenses the air_, and diminishes its capacity for holding vapour in solution.

Q. _Does more rain fall in SUMMER or in WINTER time?_

A. There are _more rainy days_ from September to March; but _heavier_ rains between March and September.

Q. _Why are there MORE RAINY DAYS from September to March, than from March to September?_

A. Because the temperature of the air is _constantly decreasing_, and its capacity for vapour decreases also; in consequence of which, it is perpetually obliged to _part with some of its vapour_ in rain.

Q. _In what PART of the WORLD does RAIN fall MOST ABUNDANTLY?_

A. Near the _equator_; and the quant.i.ty of rain _decreases_ as we approach the _poles_.

Q. _Why does MORE RAIN fall at the EQUATOR than at the POLES?_

A. Because the _contrast_ between the _night and day_ is very great. The hot air _absorbs moisture very abundantly_ during the day; and when the cold night _condenses_ the air, it is unable to _retain the moisture imbibed_, and some of it falls in rain.

CHAPTER XXV.

WATER.

Q. _What is WATER?_

A. Water is composed of _two gases_, oxygen and hydrogen.

(In 9 lbs. of water, 8 are oxygen, and 1 is hydrogen.)

Q. _Why is WATER FLUID?_

A. Because its particles are kept separate by _latent heat_; but when a certain quant.i.ty of this latent heat is driven out, _water becomes solid_, and is called ice.

Q. _How can WATER be converted into a GAS?_

A. By increasing its _latent heat_, the particles, of water are again _subdivided into invisible steam_.

Q. _Why is PUMP water called HARD water?_

A. Because it is laden with foreign matters, and will not readily _dissolve substances_ immersed in it.

Q. _What makes PUMP-water HARD?_

A. Because when it filters through the earth, it becomes impregnated with _sulphate of lime_, and many other impurities from the _earths and minerals_ with which it comes in contact.

Q. _Why is it difficult to WASH our HANDS clean with HARD water?_

A. Because the _soda of the soap_ combines with the _sulphuric acid_ of the hard water, and the _oil of the soap_ with the _lime_, and float in flakes on the top of the water.

N.B. Sulphate of lime consists of sulphuric acid and lime.

Q. _Why is it difficult to wash in SALT WATER?_

A. Because salt water contains _muriatic acid_; and the _soda of soap_ combines with the _muriatic acid of the salt water_, and produces a cloudiness.

Q. _Why does a BLACK HAT turn RED at the SEA SIDE?_

A. The _muriatic acid of the sea-water_ disturbs the _gallic acid of the black dye_, and turns it _red_.