l-2s 



wi-c in tc-nnu; tin- ci >nil nist il );lit v < t the hydrogen an explosion inav 

 occur from the formation of detonating ^as (the mixture of the oxygon 

 of t he air ^ it h the hydr i^en ).'" 



Hydrogen, which i>> contained in water, and which therefore can 

 he obtained from it. i> also Contained in manv oilier substances, ' s and 

 may be obtained from Them. A-> examples of this, it may le men- 

 tioned (l)that a mixture of formate of sodium. < ' 1 1 Na< ) .,, and canst ic 

 soda. Xa 1 1 <>. when heated to redness, forms sodium carbonate. Na.,('< ).,. 

 and hydrogen. II., : ''' i'2) tiiat a number of organic -ub.-tances are 

 deci iinj M isei 1 at a red heat, tormin^ hvdroi^en, amon^ other leases, and 

 thus it is that hydrogen is contiiined in ordinary liu'htinu' u'as. 



( 'harcoal itself liberate- hydrogen from steam at a hiudi tempera - 

 ture : -" but the reaction which here takes place i- distinguished by a 

 certain complexity, and will therefore be considered later. 



cylinder or tla-k \villi the i;-a>. it i- tilled \vitli water ami inverted in tin 1 funnel, and 

 tin -t ' >| >-<'>(]< - // and '/ opened. Then water will run I hrouiih n, and the uM- \\"ill e-cape 

 from the gasholder into tin- cylinder thromjh //. 



'' Wlirn it i-; I'ci pi ircd l<> pri-parc hydroj/pn in larj^v quantities for lillinLT lialloon.-. 

 cnjipcr vc>sds or \voodcii casks lined \villi lead are eniployed : they are tilled with -crap 

 i ron . over which dilute sui ] >hu ri<- acid is poured. The hydn i^'eii general ed from a numl per 

 i it ca >K'~ i> ca rried t hrou^'h lead pi pe- into special ca>l\'- contain 1 1 in' wat er M n order to cool 



the ua- 1 and lii in order to remove acid fuincsl. To avoid loss of ^a- all the point- 



are made hermetic, ill v ti-'ht with a paste of piaster or tar. In order to till his ^i;_'ant ic 

 halloon lot' i2.".iHio ciihic metre, capacity i. (iit'fard. in ISjS, constriu-tcd a coinjilicale.l 

 apparatn- f"!' _;'! \'inu r a cont iniious supply of hydrogen, in \\hic!i a mixture of sulphuric 

 acid and water wa- continually run into \c-sel- containiiiL; iron, and from which the 

 solution of iron sulphate formed \\a- continually drawn ot't. \\heii coal ua-. ex- 

 tracted fromcoal. isemjiloyed 1'. >r tilliiiLT halloo us it should lie a> li^lit. or a > rich in hydrogen. 

 a~ po^-ilde. I''or this reason, only the la-t portion- of the ^as comin.u from the retort- 

 are collected, and. hcside- thi-. M i- then sometimes passed through red-hot vesseU. in 



urdei' to decomjiosc the liydrocarl - a- much as possible; charcoal i- deposited in the 



red-hot vosels. and hydros-ell remain- as rus. Coal -'a- may he yet furt her enriched 

 in hydro-'en. and couseinient 1\ rendered lighter, hy passing it o\er an ignited mixture ot 

 charcoal and lime. 



i- oi the metal-, only a very few comhine with hydrogen i for exam).le. sodium). 

 ;11 ,d j_rj\,. >iilstaiices which are ea-il\ <leco)np,,sed. Of the iion-melals, tin- halo- 



tahle. wli : ' lho-e ol l.roniine ami iodine are easily dec po.ed. e-pecialh the 



Iiydro'_'en compound- ot different coinpo-ition .,,,,] proper! ie-. Imt they are all le-s -talili 

 1),,,,, '/.ater. The numliei' "t the carl. on compound- of hydrogen is e 'moil-, l.ut tln-ri 



hylr..'_'i'-n. at a ivd heal. 



I , ,,,, , . |, . , , , i i : , ei | nation ( 'Na !l( ) NallO CNa .< >.-, II . may \,< 



, ... ,.,,., | , . ,. ||,, -,, , , mpo ition o| ,-opp. r , arhoiiate or mercurx oxid. 



,. r ,-fo|'e I'ictet f, !. I ide 11-i- ot i ! t o oht a i 11 1 1 \ < 1 1'o^el I 1 1 1 1 d e r ;J lea 1 | .1 e -> l| re 



< The reaction li.-tw 'h, \ a n< I n peri MM 1 . I team i-adoiihleoue tliat i-. thi-n 



,,a\ IM lol'ined eilhel- i nl.oiii' o\lde.< (I a ccol'd ill- t o t 1 ie e. I lla t ioll I I ,< ) (' II . C'Ol, O] 



