<20& MARKING COLOUR FOR LINEN*, &C. 



no remark to make on this fubjecl, but advert to it principally 

 with a view to mention an eftecl not generally known, but/ 

 calculated to fhew the agitation, which a (mall quantity of af- 

 Remarkable ef- tending air can produce in water. If a i'wimmer (ill his lung?, 

 feci of agitation with air by inhaling as much as poffible, and then dive down 

 duclfby Sr°" or de * cend into the wattr t0 lhe deDth (>i fourteen, twenty or 

 blown flowly more reet, and when at that depth flowly blow the air out of 

 through the j^ mou ^ } ie w [\\ hi m f e lf hear a roaring noile, and the fpec- 

 depth of feveral tators will fee with furprife the fur face of the water raifed mto 

 feet beneath the a roun d or conical mafs about a yard in height, with the water- 

 flowing round on all fides over a furface of (even: or eight fquare 

 feet. I have little doubt but that the noile of this rifing co- 

 lumn of water with the breaking of the bubbles of air would 

 be very remarkable in one of the ftiil evenings or nights of 

 fummer, when the efTec! of noifes is remarkably more im- 

 prefiive. than when the louder founds of the day render them 

 lek obfervable, and in many inftances altogether inaudible. 



xn. 



Experiments to aftertain the left Colour for marking the Heads of 

 Pieces of Cotton or Linen in the rough, which jhalt be capable 

 of re/ljUng the Operations of Bleaching, as ivell as the mqft 

 complicated Procejfes of Calico Printingy without ^reading 

 beyond the Limits of the Impreffion. By Mr. HauI*fmann«* 



Properties re- An order that a colour may be proper to maVk* j>iece good? 



quired in a good f every kind it is requifite that it (hould contain no fubftance 



or jnk. or drug capable of folution in alkalies ; it is equally neceffary 



that its component parts (hould not become white by oxygena- 

 tion, and that they (hould remain infoluble in acids fufficiently 

 ftrong for the bleaching procefies, as well as for the operations 

 antecedent to the calico printing. 



Oil colours are Colours com po fed of drying oil cannot therefore, as I have' 



bad becaufc they f ound be ufefu! in thefe kind of marks, becaufe they are not 

 yield to alkalies, . , J ■ 



&c. only attacked by alkaline and foapy liquids, but likewife be- 



caufe they dry (lowly, and by fpreading beyond the limits of 

 impreffion, very often occaiion fpots. 



* Annates de Chimiej LIU. 208* * ' *■ ' * u ' 

 5 If 



