His 



solutii ins \\hen ii.-> alhniiv tor hydrogen is aided bv the atlinitv of 

 livdroifeli indidi' ii>r \\alcr. In a gaseous slate Iodine docs not act 

 on hydrofoil sulphide,"'' whilst siil]iln;r is able to decompose gaseous 

 hydri"dic arid, forming hydrogen sulphide, and a compound of sulphur 

 a lid iodine \\ it h \\ hieli s\ at cr forms hydriodie acid.' ' 



If hydrogen sulphide in 1 paed through water containing iodine, the 

 reaction II S - I ., = l!l I I -f- S proceeds so long as the solution he 

 dilute : or \\itli a greater mass of iodine, so l.m-- as a solution of iodine 

 in hvdriodir acid ha\ inu a composit ion of nearly l! 1 1 I +11- -t- ( .'ll.,<) 

 (according to I '.incau i be not formed. I 1 \ -dro^vn sulphide t hen no longer 

 act- on >uch a .-.oliition. Ayhatevcr be the mass of the free iodine. There- 

 fore, only weak solution.-* of hxdriodic acid can he ohtained bv passing 

 hvdrii^eji Milplnde mio \\ater \\ith iodine. 1 ' 



To obtain 7 ' u,"a>eous h\ drobroinic and hvdriodic acids it is most 



: till fit] itr ti>l' Mllplmr lili- licit! nl t'll-inll '- ''':. ;ill(l llic llcUt (if 



:': ... -., II - 1-7 : M ( : II: II Mr -Jl. HIH! H , I... 



I-; lifiicc the l',.nii:iti<.n i'f II S u:\i- I'-- lu-;it than llial ot IK'l :i)i<l 



! i i ; . i ..:: i'...., i i.; i ii ; i:,:i < : 1 1 i . I ii <liiutr Milutiuii- 11 , > Aq '.c:'.. and (-(iiiM-inu-ntly 



: i , f > II ,S ,-M.I\I-> Inn little hfiit with 



, . -'ilutidis chluriiH'. IIIMI .inc. ami indiiii' ilccdiniiost- 



. . I - 1 1 1 < I y < > t t h i > i 1 1 1 [ 1 1 1 > 



1 i . ii - c\ idt-iit li'diu the examples cited >n 



;.''.,. intii the condition^ ni' chemical e(|iiilihn'a, it 



I,!,. 1,, i i , , ,;,!. l;\- l'dlld\\ !i:._- the I'ddtMeps of 



I ..;.-:.: tin |i|-ol)lelll \\ ill he reached : I'll! tile Udl'li ill 



. , .,,.,- dci iiMnii--, pn-cnl tlifiiiM-lvfs 



,,,;.'!.'. il, ml.! place the-e [irdlileins to (lie 



:,.,... I i .. i-_' el the I \ \: : -hi .1 Id i urn the reader's att< ntion to jiriihleiiis 



i : Id arrive ;it ! heir >d|utidii. 



. . . i k. I am lidt al.le t, t,,ni-li mi all tlice\i>t- 



' in . 



'i in i- i ' : , . i anhydride, hi a dilute ->nlu- 



iodine. ( >n ci mceiit ra I ion a rex eive 



I . ; ! . nt hii i ! e liiit part iciilar cases of 



i tin . i . i,i chemic.il mechii iiic-- \\eiv more exact and 



, . : '.;.;,.:,,, ,,| |,n paralm.. ,///// 



- . ' ' !! Ii pi-rat Ill'e. pi , - -lire, ma e . iVc.l The --I lld\ 



,,. , .,,;',.,: mi ! hdd i,| ] . t ,di t hen tore one o) the path-- for the stud v i if elii'iniciil 



\', ;, 7 i d t In ' ' ' : led li\ the possiliilil \ of (lie format ion 



i rodin tin. 



