Chapter Twenty-Nine: Firewall and Firepit (Fourth Watch)

A young, pretty daughter-in-law suddenly emerged from the inner room. By the light from the street, Chen Ying noticed tear stains on her face. She glanced at him timidly, and Chen Ying realized she must have been the one sobbing just moments before.

Seeing Chen Ying and the Tang soldiers led by Liang Zan, she quickly retreated back into the room.

Chen Ying rubbed his nose, feeling a wave of frustration. Did he really look like the type of man who would take advantage of such a situation?

In truth, one could hardly blame the young woman for her wariness. With the thirty-six rebel kings and seventy-two warlords rising in the final years of the Sui Dynasty, and over a million soldiers scattered across the country, it was often impossible to tell the difference between soldiers and bandits.

Chen Ying did not take it to heart.

The old man said, "We have meat, but there is no one left to eat it. What use is meat now?"

Chen Ying was puzzled. Liang Zan took a torch from a guard, and the light illuminated the small room as if it were daytime. It was then that Chen Ying suddenly spotted a corpse lying in the main room.

The body appeared to be that of a young man, perhaps in his twenties, his face a ghastly, bruised purple.

Seeing the body, Chen Ying’s suspicions grew.

"No need to look, Commander," the old man said, his voice cold and devoid of human emotion. Losing a son in his old age had clearly devastated him. "It is charcoal poisoning. It is simply fate."

What the old man called "charcoal poisoning" was what later generations would identify as carbon monoxide poisoning. Hemoglobin binds with carbon monoxide over two hundred times more strongly than with oxygen, and the separation process is sluggish. Once a person inhales carbon monoxide, oxygen is denied the chance to bind with the hemoglobin. This deprives tissues and cells of sufficient oxygen, leading to respiratory distress, rapid spasms, and unconsciousness. The skin on the cheeks, chest, and lips turns a cherry-red color; without timely rescue, death by respiratory failure follows quickly.

This family’s misfortune was that they had very little coal stored during the siege. The old man and his daughter-in-law had endured the freezing cold in the outer room, saving the only source of warmth for the son in the inner room. The inner space was small and poorly ventilated; the old man and his daughter-in-law in the outer room were fine, but the son in the inner room had succumbed to the gas.

"The dead cannot return. Please accept my condolences, old man," Chen Ying said quietly. He had Liang Zan leave some money behind before they departed from the tragic household.

Stepping out into the cold wind, Chen Ying felt his head clear.

In this era, people had little understanding of carbon monoxide poisoning. They generally believed that only coal was toxic, while charcoal was safe. In reality, this was a misconception; both charcoal and coal are harmless in well-ventilated conditions, but if air circulation is blocked and carbon monoxide levels in a room exceed safety limits, a harrowing tragedy is inevitable.

He could not let this happen again. Carbon monoxide poisoning usually wiped out an entire family; it was rare for a son to be the only one enjoying the warmth due to an elder’s indulgence. Moreover, now that the city was open and the common people had access to large amounts of firewood, if a tragedy occurred, it would be a disaster.

Of course, there was no accountability system at this time; even if a tragedy occurred, it would not be blamed on Chen Ying. However, his conscience would not allow it. Chen Ying returned to the Lingzhou Prefecture office, where Yang Ze was still busy writing at his desk.

Chen Ying recounted the tragedy he had witnessed.

Yang Ze replied, "Commander Chen, I shall immediately order the city magistrates and the clerks of the Prefecture to notify every household in the city!"

"Preventing charcoal poisoning is merely treating the symptoms, not the root cause," Chen Ying said.

"Then how do we treat the root cause?" Yang Ze asked, unable to fathom how one could guard against a colorless, odorless gas.

In the era Chen Ying came from, carbon monoxide poisoning was rare. In this era, however, due to a lack of knowledge, the accident rate was much higher.

Chen Ying pondered. In the winters of his time, in addition to central heating, northern households used "kang" (heated brick beds) and "fire walls." The former was common in the Northeast, while the latter appeared in the Northwest and Xinjiang. As modern heating systems took over, these primitive methods were slowly fading from history.

He could not provide modern central heating, as he lacked the means to solve the issues of plumbing and pressure. But fire walls and heated beds were simple.

Chen Ying took the brush from Yang Ze and sketched the designs on the desk. Pointing to the drawings, he explained, "Whether it is a heated bed or a fire wall, it is very simple. Any mason can build it from these plans. As long as you ensure the chimney and ventilation are correct, and crucially, that no open flame or smoke enters the room, it is safe."

Yang Ze remarked, "I had no idea you were not only a master of military strategy but also an expert in such diverse arts!"

"Er..." Chen Ying had assumed these were common knowledge. Seeing Yang Ze’s surprise, he realized that due to limited information dissemination in this era, what were basic concepts to him were profound wisdom here.

Yang Ze was a man of action. Despite it being New Year's Eve, he immediately ordered the magistrates and clerks to take action. Chen Ying, utilizing the laborers and craftsmen in his army, began by retrofitting the Lingzhou Prefecture office first.

It was, as Chen Ying had claimed, remarkably simple. His quarters in the front of the office had been built long ago. Within the inner side of the old wall, the workmen built a second wall, using a mixture of sticky rice water and mud. They cut two holes in the outer wall—one for exhaust and one for fueling.

A dozen craftsmen completed the fire wall in less than an hour. They then prepared to light it with charcoal.

Seeing them reach for charcoal, Chen Ying said, "Don't use charcoal. Use coal."

A craftsman cautioned him, "Commander, coal is poisonous!"

"If there is any trouble, I will take full responsibility!"

"But—"

"Enough talk!"

Chen Ying was not just trying to save money. He held a deep, profound love for China’s mother river, which was currently suffering from severe soil erosion and frequent, devastating floods due to deforestation in the upper reaches. If he could change the people's habit of using wood charcoal to coal, he could help preserve the environment for future generations.

The craftsmen dared not defy him and complied.

By the time he finished late that night, Chen Ying was exhausted. He prepared to return to his quarters to rest. Upon entering his bedroom, he froze. A woman was sitting there—she was full-figured, with a slender waist and a high, swelling chest that strained against her pale green spring tunic, creating a perfectly alluring curve. Her face was exquisite in the lamplight, her eyes exceptionally charming. Seeing him return, she stood up, let out a soft yawn, and said coquettishly, "I am here to undress you, General."