KELP. 



431 



iMoluble 



.:.-..' 



the kelp, even t the same place, varies considerably, 

 depending, no doubt, on the circumstance* which occur 

 during the manufacture. This last circumstance ren- 

 ders it of importance, that the purchaser should always 

 be able to judge of it* value. It is shewn in the same 

 paper, that for want of some method for this purpose, 

 nigh price* are sometime* given for very indifferent 

 articles. 8 per tod was given for kelp containing 4.^ 

 per cent while 11, 11s. was given for an article con- 

 taing lea* than one per cent. It is on this ingredient 

 that the value of kelp to the soap-maker depends. 



Tne following statement is given, of the composition 

 of the uuoluble part of kelp, as ascertained by experi- 

 ment. 



Striphurrttcd hydrogen and carbonic acid, 

 CaAoo, ..... 



Sulpl.unc acid ...... 



he gives a table of the specific gravities of solutions of 

 different degrees of strength, varying from 1 to 20 per 

 cent. 



A solution containing 



1 1 per cent, has a spe- 



viric gravity of 1088.3 



12 1089.5 



* >n r -' 1 



SUf* principally soar, making, Hajrtifcag. 

 * The s<p niaker \mdbleacher use 



Iron, 



The quantity of uncombined alkali in barilla, was 

 found to be more uniform than in kelp, and the average 

 about 1 1 per cent. The whole soluble matter amount- 

 ed to from one-half to two-thirds. In all respects, the 

 number and kind of ingredient* in kelp and barilla are 

 the same, with the exception of iodine, which is con- 

 in kelp, Imt not in barilla. 



The manufacture* in which kelp is employed, arc 

 ipally soap-making, bleaching, and giaw-making. 

 soap maker and bleacher use the soluble parts 

 alone ; and these are only so far valuable to them, as 

 they contain uncombined alkali, or can be made to 

 yield it After the toda it extracted, an additional 

 quantity of this alkali may be procured from the twl- 

 pbates. For thia purpose the spent ate* are mixed 

 with saw-dust, or waste tanner's bark, and a portion of 

 lime M added ; these are exposed to an intense heat, 

 with the free accea* of air, in a reverberatory furnace. 

 The effect of this process i* to decompose the sul- 

 phuric acid, in consequence of which the alkali i* aet 

 free ; and though thi* alkali should consist partly of 

 potaass, yet it is the soda that it obtained free, at the 

 potaata evolved detaches it from the muriate of coda, 

 by combining with the acid of this salt. The com- 

 bustion of the carbonaoeciu matter employed produces 

 a quantity of carbonic acid, by uniting with the oyxgen 

 of the sulphuric, and thi* carbonic acid combines with 

 more or let* of the alkali, set free from the more pow- 

 erful acidt. The nulphur obtained by the iltfiiamtti 

 tion of the sulphuric acid, unites witli the lime to form 

 a tulphuret. The muriate of potaeta, formed in 



process, U obtained by evaporation, ami purchatail by 

 the alum manufacturer*. The remainint; taw contain 



iodine, which may be separated copiously, by the pre- 

 ce*ae described under our article IODINE, to which the 

 reader it referred for a full account of that ilngaial 

 sutntanc*. 



As the soluble matter i* thus valuable, and it i* of 

 lit f * ~Mia- some importance to be able to determine the total quan- 

 ta? IMMSC, tity of it roBtainod in a given portion of any particular 

 kelp, Dr. Fyfe proposes, a* the readiest method of do. 

 iug tli:-, to extract it from a given weight of the kelp, 

 by mean i of a determinate proportion of water, and 

 then to use the lutuamai maann for determining the 

 'peciuc gravity of the solution. To assist this process, 



13 

 14 



15 

 16 

 IT 

 18 

 19 

 20 



109ti.fi 

 1103-5 

 1110.4 



nio'-y 



1123. 



1133.S 

 113S.1 



Two ounces of finely ground kelp may be put into a 

 tall narrow glass ; on this six ounces ot water may be 

 poured, and the height of the liquid marked on the 

 glass. It may then be boiled gently for nu hour, the 

 whole returned into the glass, and a quantity of water 

 added, till it rue* to the mark. The specific gravity 

 of a dear portion of this may then be ascertained, and, 

 a* six times the weight ot water was employed, the 

 proportion per cent, is to be multiplied by six. 



When the whole quantity of soluble matter is ascer- Sulphuric 

 tained, and also the quantity of uncombined alkali, or acid, 

 alkaline carbonate, it may be of use to determine the 

 proportion of sulphuric acid, by treating it with mu- 

 riate of barytes, and weighing the precipitate afforded. 

 This will ihow what proportion of alkali may be ob- 

 tained by the application of heat to the soaper's lees, 

 mixed op with saw-dust, or other carbonaceous mat- 

 ter. 



The insoluble residue of kelp, is used by the glass- 

 makers for preparing the coarser kinds of glass. When 

 obtained from the soap-boiier, it contains a quantity of 

 lime, which he has added to it, anil this earth has a con- 

 siderable share in the formation of the glass. This re- 

 sidue alao forms a valuable manure. 



In the manufacture of crown glass, keln is employed 

 in the entire state, being subjected to the process of 

 comminution, but to no chemical separation of its in- 

 gredient*, except that the carbon and sulphur arc 

 driven off by the application of a strong heat, and this 

 i* done after it is mixed with the sand, which is to 

 form the glass along with it. 



The kelp procured from the Fucttt f''aicvlv*ut, is in Comparison 

 largest quantity, and is generally in most esteem for its of lhr '' 'l' 

 quality. The'Fucw NoJimu affords a kelp of equal {" 

 value, but in smaller quantity. The l-'ncut Srrratwt is r 

 in both these particulars less productive ; and the /'- 

 cut Difilatut still less. The last forms the principal 

 part of the drift ware, which is regarded as affording 

 kelp of an inferior quality, though to this there are oc- 



Keip procured from fuci which have l>een exposed Effect of 

 to rain during the process of drying, is fotind inferior rain. 

 in ita quality to that which has escaped such expo- 

 Mire. 



Fuci cut when, two or three years old, yield more Age of the 

 kelp in proportion to its bulk, than when suffered to fucl - 

 stand longer. 



I In- alkali, free or carbonated, contained in kelp, U Origin of 

 the product of the burning process; none being ob- ?"J. fuci a '~ 

 taincd from tea-weed by subjecting it to the action ' 

 of boiling water. It is found, however, that the ac- 

 cost of air is not necessary to the evolution of the soda, 

 and that it is equally procured by strong heat applied 

 to the weed, in close as in open vessels. The heat 

 acts by the destruction of the sulphates, -which is cf. 



