To Thomas Archer Hirst   Mar 30 1849

[(Mar 30 1849)]¹

My Dear Tommy & Jemmy² –

I wish I could write phonography³ or some other condensation of penmanship that so I might throw all I have to say to you into half a dozen lines – you will find the following sketch of some use in your researches. 1^st you must procure some sulphuret of iron, or rather you must make it yourselves, the process is described in Fresenius⁴ §26 page 30 German edition, from this sulphuretted hydrogen is easily procured a most valuable reagent; you must also make some hydrosulphuret of ammonia, the process is in Fresenius §27. These two reagents are indispensable – well you take the fluid you wish to seek and make it weakly acid with hydrochloric (muriatic) acid, add, sulphuretted hydrogen – it gives no precipitate (I omit all until I reach the 4^th group) add ammonia to the same fluid until it is converted from acid into alkaline and then add hydrosulphuret of ammonia, the following substances are precipitated –

Nickel Cobalt } black Iron

Manganese – flesh color – Aluminum } Zinc – white – oxide of chromium

you dissolve the whole precipitate in hydrochloric acid and the following scheme will shew you how to manage the solution –

1^st add solution of potash⁵

In solution Zink,6 Alumina, chromium boils			Precipitated Nickel Cobalt Manganese and Iron; dissolve this precipitate again in hydrochloric acid and add Salammoniac7 and ammonia
precipitated by boiling chromium	remains dissolved Zink & Alumina		In Solution Cobalt, Nickel, Manganese add acetic acid until the solution is weakly sour, heat, and then lead a stream of sulphuretted hyd. gas thro the solution N.B. it must continue for about 10 minutes		Precipitated Iron a reddish brown
	carry sul. hyd. gas thro solution
	precip. Lime	dissolves Alumina
			Precipitated Nickel, Cobalt For the present I will say no more of Nickel and cobalt –	In Solution Manganese you can prove whether Manganese is there or not by adding hyd. sulp. of ammonia, it gives a precipitate

Supposing hyd. sul. of ammonia gave no precipitate, proceed as follows, add carbonate of ammonia, if 2^nd group be there they are precipitated with the exception of magnesia to test for the latter you <must> take a little of the filtrate and add phosphate of <Soda> if there it will be <precipitated> it must be <separated of> course by filtration and the remaining fluid searched for the 1^st group. Suppose carbonate of amm. gave a precipitate – Dissolve in hyd. chlo ac. and divide solution into 3 parts – 1^st evaporate to dryness, add alcohol, set on fire, if [strontion] be present the edges of the flame are red. 2^nd add solution of sulphate of lime. Barytes precipitated. 3^rd add sulphuric acid, which seperates the Barytes & [Strontion] and leaves almost the whole of the lime behind – to detect the latter add oxalic acid, or oxalate of potash – lime precipitated –

With regard to the substances of the fourth group you must buy peroxide of manganese, for iron & zinc you can take a bit of the metal & dissolve it in the proper acid, dilute nitric acid for instance, not too dilute, you know a salt is a compound of an acid and a base. well as salt which contains an atom of base for every atom of acid and vice versa is a neutral salt – if the acid predominate it is an acid salt, if the base it is a basic salt. for example NaO CO₂ is a neutral salt, – but ${\overline{T}}_2{\mathrm{\text{NH}}}_4\mathrm{\text{HO}}$ is an acid salt there being 2 atoms of acid to one of base (vide Fres. at the end of am^a. 1^st group, in German edition it is wrong T being only once repeated) for examples of Basic Salts – see Magnesia. – carbonate of potass & phosphate of soda [throw] such down – in each case you will find the number of atoms of the base predominant – this division is altogether independent of the effect of the salts upon litmus – a neutral salt will sometimes redden it – See Zinc 4^th group –

I wish I could galvanize time as people do india rubber to improve its elasticity – if it could be so stretched I would write to you at greater length, thus far however you have no cause to complain. Tom’s discovery of the young chemists⁸ in Halifax was I suppose attended with feelings similar to what mine would be should I discover myself some fine day unexpectedly surrounded by a troop of 31^st cousins⁹ here in Germany – The spring is beginning to peep in upon us, and nature is preparing for new life – man on the contrary sharpens his implements of death¹⁰ – troops of Bavarian dragoons¹¹ pass daily on their way to Schleswig Holstein,¹² Hesse Cassel¹³ sends 6.000 in a week or two they will be slashing away amid blood fire and vapour of smoke – little children in the streets are shouting at the top of their voices

Schleswig Holstein Stammverwandt

Bleibe treu mein vaterland¹⁴

You can guess the meaning. Tom has covered the tracing paper very judiciously <the> change of ink was no improvement – as from front and rear the strength is nearly alike. We have now our vacation, the students are all away and I devote the whole of my time in the laboratory to Electro Chemistry – it is deeply interesting, I intend to follow it up as far as it has been developed, we had a magnificent course on the subject during the winter, the whole matter was beautifully explained & illustrated by splendid experiments. here ends the neutral sheet.

believe me my Dear boys | affectionately yours | J Tyndall

A letter <reached me>¹⁵ yesterday from Tidmarsh – he is on the way to Sidney!¹⁶ poor fellow I have known him long, we <were as brothers.>¹⁷

RI MS JT/1/HTYP/20-21

RI MS JT/1/T/1018