"The boiling of the ... is another one of the essential phases of brewing. ...It is at this stage that the hop is added to the wort, but not until after the latter has boiled a sufficient time. Usually, the boiling requires four hours; at the expiration of the third hour, or still later, perhaps, the brewer will empty the contents of several large sacks full of aromatic hops into the copper, thus adding the bitter principle to the saccharine. ...At present, the average brewer fully understands that he can extract the essence of the hops without excessive boiling. The object of the boiling is: 1. To concentrate the wort; 2. To extract the essence of the hop; 3. To coagulate the unchanged albuminous substances and cause them to settle, together with the unconverted starch which if allowed to remain intact, would materially militate against the preservation of the beer. But this does not do justice to the important functions of hops... the action of this tender plant upon the wort. ...Without it, beer would be nothing more than fermented barley-juice, which... was known to the most ancient nations. Without it, beer could not be preserved for any length of time, and both in appearance and flavor would be greatly inferior to the drink of today. Hence, hops not only impart to beers their pleasantly bitter and aromatic flavor, but they also assist in clarification and produce the preservative qualities. The two principal substances which the hop-cone yields, when boiled, are lupulin and , and it must be the brewer's aim to extract these in just that proportion... The diminutive sparkling grains of the hop flower, called lupulin, are closely wrapped up in the centre of the hop cone, and should be laid bare before the plant is placed in the copper. To this end most brewers will break up the hops..."