To Thomas Archer Hirst   Feb 9th

Marburg Feb 9^th

My Dear Jemmy¹ and Tommy

My sons

Your laboratory has been an expensive affair, £2 is a high figure, I did not intend you to get Fresenius Quantitative² for some time to come, but as you have it it is safe stock; now the best way to make the laboratory cheap will be to extract the greatest possible amount of good out of it, the philosophy of this remark is so evident that you may feel it with your finger ends.

For the present never mind the experiment with potass³ and Carbonic acid – I have not done it myself; Carbonic acid is a gas, you have heard of persons in descending a coal shaft drop dead suddenly, it was through the inspiration of this noxious gas, it is expired from the lungs in respiration and thus renders air once breathed unfit for further use it is composed of two atoms of Oxygen united to one of Carbon CO₂⁴ and is thus prepared –

chalk is a carbonate of lime, composed of carbonic acid and lime, by immersing chalk in a stronger acid than CO₂ the latter is driven away and can be collected place some small lumps of chalk or pounded marble in the bottle a (you see the way the glass tube passes through the cork, by the way you can bend your glass tube over the flame of a little oil lamp) pour water in sufficient to cover it and add a little Hydrochloric acid (muriatic acid) or nitric acid, almost any acid the gas will be immediately given off and can be collected in a vessel b, it is so heavy it can be collected as shewn in the figure, it fills the glass like an invisible water, it will extinguish a lighted taper, and if a bit of candle lighted be stuck in the bottom of another glass it will be extinguished by simply pouring the CO₂ upon it like water, the agent of course is invisible. CO₂ decomposes Lime water and gives a white precipitate of Carbonate of lime, take a glass of lime water and breathe into it through a glass tube for some time, it will become milky – just try this – see fig. –

A sand bath is merely hot sand, it is good for evaporation, a water bath is simply hot or boiling water upon which a second vessel containing the substance is laid, thus you get the heat of the water without its moisture. You are perfectly right as regards the litmus paper, there is no better way of testing an acid or alkaline solution. acid of course turns it red alkali merely deepen the blue color. ‘Is the menstrum worth keeping’?⁵ No! –

The substance KO is called a base, T⁶ is an acid, bases and acids combine to form salts and in the case in question they combine in the following proportions (why they do so nobody knows you might as well ask why Jimmy’s⁷ nose is so like a button) $\mathrm{\text{KO}}\overline{T}$ + $\mathrm{\text{HO}}\overline{T}$ that is two atoms of acid to one of base, hence the name bitartrate of potass,⁸ just as you are a member of the class bipoda simply because you have two legs. I will briefly point out the reactions in the various groups which are necessary for qualitative analysis, the rest will come forward in Quantitative which is still some distance in prospect – you may for the present omit the antimoniate of potass.⁹

Ammoniac¹⁰ = Make the experiment by mixing with lime and rubbing, make the experiment by mixing with potass heating and testing for white fumes with glass rod moistened by Hydrochloric acid. NB. even though the solution should have no smell, these reagents will develop the smell, muriate of ammonia¹¹ for instance has no smell.

Barytes,¹² Test with ammonia, carbonate of ammonia or of potass and sulphuric acid – the last most important

Strontian¹³ Test as in the case of Barytes, but do not omit the burning with Alcohol – this is very much used to detect Strontian –

Lime Test as in the former cases, but dont omit oxalic acid, it is the Chief –

Magnesia¹⁴ you can try ammonia and the carbonates, but especially phosphate of soda

Alumina¹⁵ Test with ammonia and potass

Chromium Test D^o16 D^o

With Tin you will have no difficulty, you are instructed to make that sweet scented gas sulpheretted hydrogen,¹⁷ this must bubble through the solution of Tin, common tin foil can be dissolved in a little hydrochloric acid and used

Mangan¹⁸ no difficulty have you got a blow pipe?

Nickel¹⁹ no difficulty –––––––––––––––– You can make hydrosulphuret of ammonia²⁰

By this time you will be expert at the use of the reagents and do not need my assistance further. In my next I will say something as to the testing for substances in a strange solution, for instance take the pipe water of Halifax and test it with a solution of nitrate of silver the chance is that it will shew the presence of salt by turning milky²¹

I am stronger now a good deal than when I came to Marburg first.²² Change of place and regimen gave me a heavy headache for the first fortnight but that has vanished and at present I enjoy robustious vigour – I can adhere to my rule without danger, surely 7 hours are sufficient to spend in bed, when you see me again you will look upon a fine blooming young fellow, there is a seam in my forehead, if I could smooth it off with an enamel of putty it would add much to my appearance. Ellershaw²³ is like Noah’s dove, where will he rest finally? – I hope he is a good boy and endeavours to apply to his own special case the wholesome homilies he used to deliver to me long ago. Remember me fondly to Tom Perkinton,²⁴ is Rawdon²⁵ yet finished – I verily think I shall have to finish Pye Nest²⁶ myself. what a joke it would be.

I have not got an English edition of Fresenius,²⁷ a german one²⁸ lies <at> my elbow, in page 196 of which and Section 117 are to be found instructions as to the qualitative analysis of substances soluble or insoluble in Water but soluble in Hydrochloric and nitric acid. Detection of the Base – I know it is the same section in the English edition but the page doubtful, let one of you mix a few substances (known) together in water or acid and let the other test – the latter will not know what is in the mixture, and he will find the discovery a pleasure, use easy substances such as those 1^st mentioned and a few at a time <at> first. NB. you must make the experiment with soda with a blowpipe, <1 word missing> pipe shank will do temporarily, this is the best method for the detection of soda. You will find the instructions arranged like Euclid²⁹ almost, I think you will be able to understand all.

Bridges algebra³⁰ is a capital book for self instruction. I devote about 4 or 5 hours a day to mathematics, and have scampered over a tolerably wide range during the last three months. You have treated the idea of my portrait so profanely that I dont know whether to send it to you or not. does Jimmy continue to grow? has he reached my mark yet? and now I must bow myself out of the present page and make my exit with a fehle mich³¹*

*a solution at parting – I recommend myself.

One of the students³² sketched the enclosed,³³ it must satisfy you until I go to Frankfort,³⁴ he has made me as demure as a Saint –

Will Tom have the goodness to put stamps on the enclosed I will settle with him some day

RI MS JT/1/HTYP/17-18

RI MS JT/1/T/517